diff --git a/protos/generated/models/aggregated_models.proto b/protos/generated/models/aggregated_models.proto
index 92833725d43..fedf11159a0 100644
--- a/protos/generated/models/aggregated_models.proto
+++ b/protos/generated/models/aggregated_models.proto
@@ -450,6 +450,8 @@ message AggregationRangeFrom {
     double double = 1;
 
     string string = 2;
+
+    NullValue null_value = 3;
   }
 }
 message AggregationRangeTo {
@@ -457,6 +459,8 @@ message AggregationRangeTo {
     double double = 1;
 
     string string = 2;
+
+    NullValue null_value = 3;
   }
 }
 message Analyzer {
@@ -501,13 +505,20 @@ message Analyzer {
 message ArrayPercentilesItem {
   string key = 1;
 
-  optional double value = 2;
+  ArrayPercentilesItemValue value = 2;
 
   optional string value_as_string = 3;
 }
 message ArrayPercentilesItemArray {
   repeated ArrayPercentilesItem array_percentiles_item_array = 1;
 }
+message ArrayPercentilesItemValue {
+  oneof array_percentiles_item_value {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message AutoDateHistogramAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
@@ -573,7 +584,7 @@ message AvgAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -581,7 +592,7 @@ message BoolQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The clause (query) must appear in matching documents. However, unlike `must`, the score of the query will be ignored.
   repeated QueryContainer filter = 3;
@@ -604,7 +615,7 @@ message BoostingQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Floating point number between 0 and 1.0 used to decrease the relevance scores of documents matching the `negative` query.
   float negative_boost = 3;
@@ -672,7 +683,7 @@ message BucketMetricValueAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 
@@ -900,7 +911,7 @@ message CombinedFieldsQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // List of fields to search. Field wildcard patterns are allowed. Only `text` fields are supported, and they must all have the same search `analyzer`.
   repeated string fields = 3;
@@ -926,7 +937,7 @@ message CommonTermsQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional string analyzer = 3;
 
@@ -971,16 +982,16 @@ message Completion1AllOfOptionsInner {
 
   optional float score = 5;
 
-  optional string underscore_id = 6;
+  optional string x_id = 6;
 
-  optional string underscore_index = 7;
+  optional string x_index = 7;
 
   // The routing value for the document.
-  optional string underscore_routing = 8;
+  optional string x_routing = 8;
 
-  optional float underscore_score = 9;
+  optional float x_score = 9;
 
-  optional ObjectMap underscore_source = 10;
+  optional ObjectMap x_source = 10;
 }
 message CompletionAllOfOptionsInner {
   optional bool collate_match = 1;
@@ -993,16 +1004,16 @@ message CompletionAllOfOptionsInner {
 
   optional float score = 5;
 
-  optional string underscore_id = 6;
+  optional string x_id = 6;
 
-  optional string underscore_index = 7;
+  optional string x_index = 7;
 
   // The routing value for the document.
-  optional string underscore_routing = 8;
+  optional string x_routing = 8;
 
-  optional float underscore_score = 9;
+  optional float x_score = 9;
 
-  optional ObjectMap underscore_source = 10;
+  optional ObjectMap x_source = 10;
 }
 message CompletionContext {
   optional double boost = 1;
@@ -1038,16 +1049,16 @@ message CompletionSuggestAllOfOptions {
 
   optional float score = 5;
 
-  optional string underscore_id = 6;
+  optional string x_id = 6;
 
-  optional string underscore_index = 7;
+  optional string x_index = 7;
 
   // The routing value for the document.
-  optional string underscore_routing = 8;
+  optional string x_routing = 8;
 
-  optional float underscore_score = 9;
+  optional float x_score = 9;
 
-  optional ObjectMap underscore_source = 10;
+  optional ObjectMap x_source = 10;
 }
 message CompletionSuggestOption {
   optional bool collate_match = 1;
@@ -1060,16 +1071,16 @@ message CompletionSuggestOption {
 
   optional float score = 5;
 
-  optional string underscore_id = 6;
+  optional string x_id = 6;
 
-  optional string underscore_index = 7;
+  optional string x_index = 7;
 
   // The routing value for the document.
-  optional string underscore_routing = 8;
+  optional string x_routing = 8;
 
-  optional float underscore_score = 9;
+  optional float x_score = 9;
 
-  optional ObjectMap underscore_source = 10;
+  optional ObjectMap x_source = 10;
 }
 message CompletionSuggester {
   optional string analyzer = 1;
@@ -1219,7 +1230,7 @@ message ConstantScoreQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   QueryContainer filter = 3;
 }
@@ -1412,9 +1423,9 @@ message DateRangeQueryParameters {
 
   optional string lte = 4;
 
-  optional string from = 5;
+  optional DateRangeQueryParametersFrom from = 5;
 
-  optional string to = 6;
+  optional DateRangeQueryParametersTo to = 6;
 
   // The date format pattern.
   optional string format = 7;
@@ -1422,6 +1433,20 @@ message DateRangeQueryParameters {
   // The time zone identifier.
   optional string time_zone = 8;
 }
+message DateRangeQueryParametersFrom {
+  oneof date_range_query_parameters_from {
+    string string = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message DateRangeQueryParametersTo {
+  oneof date_range_query_parameters_to {
+    string string = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message DateTime {
   oneof date_time {
     string string = 1;
@@ -1455,9 +1480,9 @@ message DeleteOperation {
   optional string routing = 1;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 2;
+  optional string x_id = 2;
 
-  optional string underscore_index = 3;
+  optional string x_index = 3;
 
   optional int64 if_primary_term = 4;
 
@@ -1472,7 +1497,7 @@ message DerivativeAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 
@@ -1520,7 +1545,7 @@ message DisMaxQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // One or more query clauses. Returned documents must match one or more of these queries. If a document matches multiple queries, OpenSearch uses the highest relevance score.
   repeated QueryContainer queries = 3;
@@ -1539,7 +1564,7 @@ message DistanceFeatureQueryOneOf {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   GeoLocation origin = 3;
 
@@ -1552,7 +1577,7 @@ message DistanceFeatureQueryOneOf1 {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   string origin = 3;
 
@@ -1681,7 +1706,7 @@ message ExistsQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   string field = 3;
@@ -1731,11 +1756,11 @@ message ExtendedStatsAggregate {
 
   int64 count = 2;
 
-  double min = 3;
+  StatsAggregateBaseAllOfMin min = 3;
 
-  double max = 4;
+  StatsAggregateBaseAllOfMax max = 4;
 
-  double avg = 5;
+  StatsAggregateBaseAllOfAvg avg = 5;
 
   double sum = 6;
 
@@ -1747,19 +1772,19 @@ message ExtendedStatsAggregate {
 
   optional string sum_as_string = 10;
 
-  double sum_of_squares = 11;
+  ExtendedStatsAggregateBaseAllOfSumOfSquares sum_of_squares = 11;
 
-  double variance = 12;
+  ExtendedStatsAggregateBaseAllOfVariance variance = 12;
 
-  double variance_population = 13;
+  ExtendedStatsAggregateBaseAllOfVariancePopulation variance_population = 13;
 
-  double variance_sampling = 14;
+  ExtendedStatsAggregateBaseAllOfVarianceSampling variance_sampling = 14;
 
-  double std_deviation = 15;
+  ExtendedStatsAggregateBaseAllOfStdDeviation std_deviation = 15;
 
-  double std_deviation_population = 16;
+  ExtendedStatsAggregateBaseAllOfStdDeviationPopulation std_deviation_population = 16;
 
-  double std_deviation_sampling = 17;
+  ExtendedStatsAggregateBaseAllOfStdDeviationSampling std_deviation_sampling = 17;
 
   optional StandardDeviationBounds std_deviation_bounds = 18;
 
@@ -1781,11 +1806,11 @@ message ExtendedStatsAggregateBase {
 
   int64 count = 2;
 
-  double min = 3;
+  StatsAggregateBaseAllOfMin min = 3;
 
-  double max = 4;
+  StatsAggregateBaseAllOfMax max = 4;
 
-  double avg = 5;
+  StatsAggregateBaseAllOfAvg avg = 5;
 
   double sum = 6;
 
@@ -1797,19 +1822,19 @@ message ExtendedStatsAggregateBase {
 
   optional string sum_as_string = 10;
 
-  optional double sum_of_squares = 11;
+  ExtendedStatsAggregateBaseAllOfSumOfSquares sum_of_squares = 11;
 
-  optional double variance = 12;
+  ExtendedStatsAggregateBaseAllOfVariance variance = 12;
 
-  optional double variance_population = 13;
+  ExtendedStatsAggregateBaseAllOfVariancePopulation variance_population = 13;
 
-  optional double variance_sampling = 14;
+  ExtendedStatsAggregateBaseAllOfVarianceSampling variance_sampling = 14;
 
-  optional double std_deviation = 15;
+  ExtendedStatsAggregateBaseAllOfStdDeviation std_deviation = 15;
 
-  optional double std_deviation_population = 16;
+  ExtendedStatsAggregateBaseAllOfStdDeviationPopulation std_deviation_population = 16;
 
-  optional double std_deviation_sampling = 17;
+  ExtendedStatsAggregateBaseAllOfStdDeviationSampling std_deviation_sampling = 17;
 
   optional StandardDeviationBounds std_deviation_bounds = 18;
 
@@ -1825,6 +1850,55 @@ message ExtendedStatsAggregateBase {
 
   optional StandardDeviationBoundsAsString std_deviation_bounds_as_string = 24;
 }
+message ExtendedStatsAggregateBaseAllOfStdDeviation {
+  oneof extended_stats_aggregate_base_all_of_std_deviation {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message ExtendedStatsAggregateBaseAllOfStdDeviationPopulation {
+  oneof extended_stats_aggregate_base_all_of_std_deviation_population {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message ExtendedStatsAggregateBaseAllOfStdDeviationSampling {
+  oneof extended_stats_aggregate_base_all_of_std_deviation_sampling {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message ExtendedStatsAggregateBaseAllOfSumOfSquares {
+  oneof extended_stats_aggregate_base_all_of_sum_of_squares {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message ExtendedStatsAggregateBaseAllOfVariance {
+  oneof extended_stats_aggregate_base_all_of_variance {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message ExtendedStatsAggregateBaseAllOfVariancePopulation {
+  oneof extended_stats_aggregate_base_all_of_variance_population {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message ExtendedStatsAggregateBaseAllOfVarianceSampling {
+  oneof extended_stats_aggregate_base_all_of_variance_sampling {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message ExtendedStatsAggregation {
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   optional string field = 1;
@@ -1844,11 +1918,11 @@ message ExtendedStatsBucketAggregate {
 
   int64 count = 2;
 
-  double min = 3;
+  StatsAggregateBaseAllOfMin min = 3;
 
-  double max = 4;
+  StatsAggregateBaseAllOfMax max = 4;
 
-  double avg = 5;
+  StatsAggregateBaseAllOfAvg avg = 5;
 
   double sum = 6;
 
@@ -1860,19 +1934,19 @@ message ExtendedStatsBucketAggregate {
 
   optional string sum_as_string = 10;
 
-  double sum_of_squares = 11;
+  ExtendedStatsAggregateBaseAllOfSumOfSquares sum_of_squares = 11;
 
-  double variance = 12;
+  ExtendedStatsAggregateBaseAllOfVariance variance = 12;
 
-  double variance_population = 13;
+  ExtendedStatsAggregateBaseAllOfVariancePopulation variance_population = 13;
 
-  double variance_sampling = 14;
+  ExtendedStatsAggregateBaseAllOfVarianceSampling variance_sampling = 14;
 
-  double std_deviation = 15;
+  ExtendedStatsAggregateBaseAllOfStdDeviation std_deviation = 15;
 
-  double std_deviation_population = 16;
+  ExtendedStatsAggregateBaseAllOfStdDeviationPopulation std_deviation_population = 16;
 
-  double std_deviation_sampling = 17;
+  ExtendedStatsAggregateBaseAllOfStdDeviationSampling std_deviation_sampling = 17;
 
   optional StandardDeviationBounds std_deviation_bounds = 18;
 
@@ -2219,7 +2293,7 @@ message FunctionScoreQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional FunctionBoostMode boost_mode = 3;
 
@@ -2249,7 +2323,7 @@ message FuzzyQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Maximum number of variations created.
   optional int32 max_expansions = 3;
@@ -2279,7 +2353,7 @@ message GeoBoundingBoxQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional GeoExecution type = 3;
 
@@ -2379,7 +2453,7 @@ message GeoDistanceQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   string distance = 3;
 
@@ -2491,7 +2565,7 @@ message GeoPolygonQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional GeoValidationMethod validation_method = 3;
 
@@ -2509,7 +2583,7 @@ message GeoShapeQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Set to `true` to ignore an unmapped field and not match any documents for this query. Set to `false` to throw an exception if the field is not mapped.
   optional bool ignore_unmapped = 3;
@@ -2590,7 +2664,7 @@ message HasChildQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Set to `true` to ignore an unmapped field and not match any documents for this query. Set to `false` to throw an exception if the field is not mapped.
   optional bool ignore_unmapped = 3;
@@ -2614,7 +2688,7 @@ message HasParentQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Set to `true` to ignore an unmapped field and not match any documents for this query. Set to `false` to throw an exception if the field is not mapped.
   optional bool ignore_unmapped = 3;
@@ -2895,9 +2969,9 @@ message HistogramBucket {
   optional string key_as_string = 3;
 }
 message HistogramOrder {
-  optional SortOrder underscore_count = 1;
+  optional SortOrder x_count = 1;
 
-  optional SortOrder underscore_key = 2;
+  optional SortOrder x_key = 2;
 }
 message Hit {
   optional ObjectMap fields = 1;
@@ -2913,42 +2987,49 @@ message Hit {
   repeated FieldValue sort = 6;
 
   // The type of document or resource.
-  optional string underscore_type = 7;
+  optional string x_type = 7;
 
-  optional string underscore_index = 8;
+  optional string x_index = 8;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 9;
+  optional string x_id = 9;
 
-  optional double underscore_score = 10;
+  optional HitXScore x_score = 10;
 
-  optional Explanation underscore_explanation = 11;
+  optional Explanation x_explanation = 11;
 
-  optional NestedIdentity underscore_nested = 12;
+  optional NestedIdentity x_nested = 12;
 
-  repeated string underscore_ignored = 13;
+  repeated string x_ignored = 13;
 
-  optional string underscore_shard = 14;
+  optional string x_shard = 14;
 
-  optional string underscore_node = 15;
+  optional string x_node = 15;
 
-  optional string underscore_routing = 16;
+  optional string x_routing = 16;
 
-  optional ObjectMap underscore_source = 17;
+  optional ObjectMap x_source = 17;
 
   // The sequence number of the document.
-  optional int64 underscore_seq_no = 18;
+  optional int64 x_seq_no = 18;
 
-  optional int64 underscore_primary_term = 19;
+  optional int64 x_primary_term = 19;
 
-  optional int64 underscore_version = 20;
+  optional int64 x_version = 20;
+}
+message HitXScore {
+  oneof hit_x_score {
+    NullValue null_value = 1;
+
+    double double = 2;
+  }
 }
 message HitsMetadata {
   optional HitsMetadataTotal total = 1;
 
   repeated HitsMetadataHitsInner hits = 2;
 
-  optional float max_score = 3;
+  optional HitsMetadataMaxScore max_score = 3;
 }
 message HitsMetadataHitsInner {
   optional ObjectMap fields = 1;
@@ -2964,46 +3045,53 @@ message HitsMetadataHitsInner {
   repeated FieldValue sort = 6;
 
   // The type of document or resource.
-  optional string underscore_type = 7;
+  optional string x_type = 7;
 
-  optional string underscore_index = 8;
+  optional string x_index = 8;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 9;
+  optional string x_id = 9;
 
-  optional double underscore_score = 10;
+  optional HitXScore x_score = 10;
 
-  optional Explanation underscore_explanation = 11;
+  optional Explanation x_explanation = 11;
 
-  optional NestedIdentity underscore_nested = 12;
+  optional NestedIdentity x_nested = 12;
 
-  repeated string underscore_ignored = 13;
+  repeated string x_ignored = 13;
 
-  optional string underscore_shard = 14;
+  optional string x_shard = 14;
 
-  optional string underscore_node = 15;
+  optional string x_node = 15;
 
-  optional string underscore_routing = 16;
+  optional string x_routing = 16;
 
-  optional ObjectMap underscore_source = 17;
+  optional ObjectMap x_source = 17;
 
   // The sequence number of the document.
-  optional int64 underscore_seq_no = 18;
+  optional int64 x_seq_no = 18;
 
-  optional int64 underscore_primary_term = 19;
+  optional int64 x_primary_term = 19;
 
-  optional int64 underscore_version = 20;
+  optional int64 x_version = 20;
 }
 message HitsMetadataJsonValue {
   optional HitsMetadataTotal total = 1;
 
   repeated HitsMetadataJsonValueAllOfHits hits = 2;
 
-  optional float max_score = 3;
+  optional HitsMetadataMaxScore max_score = 3;
 }
 message HitsMetadataJsonValueAllOfHits {
   optional ObjectMap source = 1 [json_name = "_source"];
 }
+message HitsMetadataMaxScore {
+  oneof hits_metadata_max_score {
+    NullValue null_value = 1;
+
+    float float = 2;
+  }
+}
 message HitsMetadataTotal {
   oneof hits_metadata_total {
     TotalHits total_hits = 1;
@@ -3097,7 +3185,7 @@ message HybridQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   repeated QueryContainer queries = 3;
 
@@ -3129,7 +3217,7 @@ message IdsQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   repeated string values = 3;
 }
@@ -3138,9 +3226,9 @@ message IndexOperation {
   optional string routing = 1;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 2;
+  optional string x_id = 2;
 
-  optional string underscore_index = 3;
+  optional string x_index = 3;
 
   // The pipeline ID for preprocessing documents. When the index has a default ingest pipeline specified, then setting the value to `_none` disables the default ingest pipeline for this request. When a final pipeline is configured, that pipeline will always run, regardless of the value of this parameter.
   optional string pipeline = 4;
@@ -3167,16 +3255,16 @@ message InlineGetDictUserDefined {
   bool found = 2;
 
   // The sequence number of the document.
-  optional int64 underscore_seq_no = 3;
+  optional int64 x_seq_no = 3;
 
   // The primary term of the document.
-  optional int32 underscore_primary_term = 4;
+  optional int32 x_primary_term = 4;
 
   // The routing value for the document.
-  optional string underscore_routing = 5;
+  optional string x_routing = 5;
 
   // The source of the document.
-  optional ObjectMap underscore_source = 6;
+  optional ObjectMap x_source = 6;
 }
 message InlineScript {
   // Specifies any named parameters that are passed into the script as variables.  Use parameters instead of hard-coded values to decrease compilation time.
@@ -3226,7 +3314,7 @@ message InnerHits {
 
   optional bool version = 15;
 
-  optional SourceConfig underscore_source = 16;
+  optional SourceConfig x_source = 16;
 }
 message InnerHitsResult {
   HitsMetadata hits = 1;
@@ -3331,7 +3419,7 @@ message IntervalsQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional IntervalsAllOf all_of = 3;
 
@@ -3399,6 +3487,8 @@ message KeyedPercentilesValue {
     double double = 1;
 
     string string = 2;
+
+    NullValue null_value = 3;
   }
 }
 message KeyedPercentilesValueMap {
@@ -3417,7 +3507,7 @@ message KnnQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   repeated float vector = 3;
 
@@ -3551,12 +3641,12 @@ message LikeDocument {
   optional VersionType version_type = 6;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 7;
+  optional string x_id = 7;
 
-  optional string underscore_index = 8;
+  optional string x_index = 8;
 
   // The type of document or resource.
-  optional string underscore_type = 9;
+  optional string x_type = 9;
 }
 message LinearInterpolationSmoothingModel {
   double bigram_lambda = 1;
@@ -3636,13 +3726,13 @@ message MatchAllQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 }
 message MatchBoolPrefixQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Analyzer used to convert the text in the query value into tokens.
   optional string analyzer = 3;
@@ -3673,13 +3763,13 @@ message MatchNoneQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 }
 message MatchPhrasePrefixQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Analyzer used to convert text in the query value into tokens.
   optional string analyzer = 3;
@@ -3701,7 +3791,7 @@ message MatchPhraseQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Analyzer used to convert the text in the query value into tokens.
   optional string analyzer = 3;
@@ -3720,7 +3810,7 @@ message MatchQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Analyzer used to convert the text in the query value into tokens.
   optional string analyzer = 3;
@@ -3813,7 +3903,7 @@ message MaxAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -3844,7 +3934,7 @@ message MedianAbsoluteDeviationAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -3873,7 +3963,7 @@ message MinAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -3955,7 +4045,7 @@ message MoreLikeThisQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The analyzer that is used to analyze the free form text. Defaults to the analyzer associated with the first field in fields.
   optional string analyzer = 3;
@@ -4274,7 +4364,7 @@ message MultiMatchQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Analyzer used to convert the text in the query value into tokens.
   optional string analyzer = 3;
@@ -4417,13 +4507,13 @@ message NestedIdentity {
 
   int32 offset = 2;
 
-  optional NestedIdentity underscore_nested = 3;
+  optional NestedIdentity x_nested = 3;
 }
 message NestedQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Set to `true` to ignore an unmapped field and not match any documents for this query. Set to `false` to throw an exception if the field is not mapped.
   optional bool ignore_unmapped = 3;
@@ -4454,7 +4544,7 @@ message NeuralQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional string query_text = 3;
 
@@ -4545,6 +4635,8 @@ message NumberRangeQueryParametersFrom {
     double double = 1;
 
     string string = 2;
+
+    NullValue null_value = 3;
   }
 }
 message NumberRangeQueryParametersTo {
@@ -4552,6 +4644,8 @@ message NumberRangeQueryParametersTo {
     double double = 1;
 
     string string = 2;
+
+    NullValue null_value = 3;
   }
 }
 message NumericDecayPlacement {
@@ -4573,9 +4667,9 @@ message OperationBase {
   optional string routing = 1;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 2;
+  optional string x_id = 2;
 
-  optional string underscore_index = 3;
+  optional string x_index = 3;
 }
 message OperationContainer {
   optional IndexOperation index = 1;
@@ -4612,7 +4706,7 @@ message ParentIdQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The unique identifier for a resource.
   optional string id = 3;
@@ -4719,7 +4813,7 @@ message PercolateQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional ObjectMap document = 3;
 
@@ -4852,15 +4946,15 @@ message PhraseSuggester {
 }
 message PinnedDoc {
   // The unique identifier for a resource.
-  string underscore_id = 1;
+  string x_id = 1;
 
-  string underscore_index = 2;
+  string x_index = 2;
 }
 message PinnedQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   QueryContainer organic = 3;
 
@@ -4894,7 +4988,7 @@ message PrefixQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional MultiTermQueryRewrite rewrite = 3;
 
@@ -4933,7 +5027,7 @@ message QueryBase {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 }
 message QueryBreakdown {
   int64 advance = 1;
@@ -5120,7 +5214,7 @@ message QueryStringQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // If `true`, the wildcard characters `*` and `?` are allowed as the first character of the query string.
   optional bool allow_leading_wildcard = 3;
@@ -5262,7 +5356,7 @@ message RangeQueryBase {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional RangeRelation relation = 3;
 }
@@ -5270,7 +5364,7 @@ message RangeQueryOneOf {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional RangeRelation relation = 3;
 
@@ -5296,7 +5390,7 @@ message RangeQueryOneOf1 {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional RangeRelation relation = 3;
 
@@ -5308,9 +5402,9 @@ message RangeQueryOneOf1 {
 
   optional string lte = 7;
 
-  optional string from = 8;
+  optional DateRangeQueryParametersFrom from = 8;
 
-  optional string to = 9;
+  optional DateRangeQueryParametersTo to = 9;
 
   // The date format pattern.
   optional string format = 10;
@@ -5346,7 +5440,7 @@ message RankFeatureQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   string field = 3;
@@ -5420,7 +5514,7 @@ message RegexpQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Allows case insensitive matching of the regular expression value with the indexed field values when set to `true`. When `false`, case sensitivity of matching depends on the underlying field's mapping.
   optional bool case_insensitive = 3;
@@ -5471,23 +5565,23 @@ message ResponseItem {
   optional InlineGetDictUserDefined get = 5;
 
   // The document type.
-  optional string underscore_type = 6;
+  optional string x_type = 6;
 
   // The document ID associated with the operation.
-  optional string underscore_id = 7;
+  optional string x_id = 7;
 
   // The name of the index associated with the operation. If the operation targets a data stream, this is the backing index into which the document was written.
-  string underscore_index = 8;
+  string x_index = 8;
 
   // The primary term assigned to the document for the operation.
-  optional int64 underscore_primary_term = 9;
+  optional int64 x_primary_term = 9;
 
   // The sequence number of the document.
-  optional int64 underscore_seq_no = 10;
+  optional int64 x_seq_no = 10;
 
-  optional ShardInfo underscore_shards = 11;
+  optional ShardInfo x_shards = 11;
 
-  optional int64 underscore_version = 12;
+  optional int64 x_version = 12;
 }
 message ResponseItemMap {
   map<string, ResponseItem> response_item_map = 1;
@@ -5572,7 +5666,7 @@ message ScriptQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   Script script = 3;
 }
@@ -5583,7 +5677,7 @@ message ScriptScoreQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Documents with a score lower than this floating point number are excluded from the search results.
   optional float min_score = 3;
@@ -5730,7 +5824,7 @@ message SearchRequest {
   // Stats groups to associate with the search. Each group maintains a statistics aggregation for its associated searches. You can retrieve these stats using the indexes stats API.
   repeated string stats = 30;
 
-  optional SourceConfig underscore_source = 31;
+  optional SourceConfig x_source = 31;
 }
 message SearchResponse {
   int64 took = 1;
@@ -5758,11 +5852,11 @@ message SearchResponse {
 
   optional bool terminated_early = 12;
 
-  ShardStatistics underscore_shards = 13;
+  ShardStatistics x_shards = 13;
 
-  optional ClusterStatistics underscore_clusters = 14;
+  optional ClusterStatistics x_clusters = 14;
 
-  optional string underscore_scroll_id = 15;
+  optional string x_scroll_id = 15;
 }
 message SearchResult {
   int64 took = 1;
@@ -5790,18 +5884,18 @@ message SearchResult {
 
   optional bool terminated_early = 12;
 
-  ShardStatistics underscore_shards = 13;
+  ShardStatistics x_shards = 13;
 
-  optional ClusterStatistics underscore_clusters = 14;
+  optional ClusterStatistics x_clusters = 14;
 
-  optional string underscore_scroll_id = 15;
+  optional string x_scroll_id = 15;
 }
 message SearchResultHits {
   optional HitsMetadataTotal total = 1;
 
   repeated SearchResultHitsAllOfHitsInner hits = 2;
 
-  optional float max_score = 3;
+  optional HitsMetadataMaxScore max_score = 3;
 }
 message SearchResultHitsAllOfHitsInner {
   optional ObjectMap fields = 1;
@@ -5817,35 +5911,35 @@ message SearchResultHitsAllOfHitsInner {
   repeated FieldValue sort = 6;
 
   // The type of document or resource.
-  optional string underscore_type = 7;
+  optional string x_type = 7;
 
-  optional string underscore_index = 8;
+  optional string x_index = 8;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 9;
+  optional string x_id = 9;
 
-  optional double underscore_score = 10;
+  optional HitXScore x_score = 10;
 
-  optional Explanation underscore_explanation = 11;
+  optional Explanation x_explanation = 11;
 
-  optional NestedIdentity underscore_nested = 12;
+  optional NestedIdentity x_nested = 12;
 
-  repeated string underscore_ignored = 13;
+  repeated string x_ignored = 13;
 
-  optional string underscore_shard = 14;
+  optional string x_shard = 14;
 
-  optional string underscore_node = 15;
+  optional string x_node = 15;
 
-  optional string underscore_routing = 16;
+  optional string x_routing = 16;
 
-  optional ObjectMap underscore_source = 17;
+  optional ObjectMap x_source = 17;
 
   // The sequence number of the document.
-  optional int64 underscore_seq_no = 18;
+  optional int64 x_seq_no = 18;
 
-  optional int64 underscore_primary_term = 19;
+  optional int64 x_primary_term = 19;
 
-  optional int64 underscore_version = 20;
+  optional int64 x_version = 20;
 }
 message SearchResultSuggestValueInner {
   int32 length = 1;
@@ -6187,7 +6281,7 @@ message SimpleQueryStringQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Analyzer used to convert text in the query string into tokens.
   optional string analyzer = 3;
@@ -6229,7 +6323,7 @@ message SimpleValueAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -6245,10 +6339,17 @@ message SingleMetricAggregateBase {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  optional double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
+message SingleMetricAggregateBaseAllOfValue {
+  oneof single_metric_aggregate_base_all_of_value {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message SlicedScroll {
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   optional string field = 1;
@@ -6357,7 +6458,7 @@ message SpanContainingQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   SpanQuery big = 3;
 
@@ -6367,7 +6468,7 @@ message SpanFieldMaskingQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   string field = 3;
@@ -6378,7 +6479,7 @@ message SpanFirstQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Controls the maximum end position permitted in a match.
   int32 end = 3;
@@ -6394,7 +6495,7 @@ message SpanMultiTermQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   QueryContainer match = 3;
 }
@@ -6402,7 +6503,7 @@ message SpanNearQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Array of one or more other span type queries.
   repeated SpanQuery clauses = 3;
@@ -6417,7 +6518,7 @@ message SpanNotQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The number of tokens from within the include span that can't have overlap with the exclude span. Equivalent to setting both `pre` and `post`.
   optional int32 dist = 3;
@@ -6436,7 +6537,7 @@ message SpanOrQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Array of one or more other span type queries.
   repeated SpanQuery clauses = 3;
@@ -6467,7 +6568,7 @@ message SpanTermQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   string value = 3;
 
@@ -6477,7 +6578,7 @@ message SpanWithinQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   SpanQuery big = 3;
 
@@ -6495,17 +6596,17 @@ enum StandardAnalyzerType {
   STANDARD_ANALYZER_TYPE_STANDARD = 1;
 }
 message StandardDeviationBounds {
-  optional double upper = 1;
+  StandardDeviationBoundsUpper upper = 1;
 
-  optional double lower = 2;
+  StandardDeviationBoundsLower lower = 2;
 
-  optional double upper_population = 3;
+  StandardDeviationBoundsUpperPopulation upper_population = 3;
 
-  optional double lower_population = 4;
+  StandardDeviationBoundsLowerPopulation lower_population = 4;
 
-  optional double upper_sampling = 5;
+  StandardDeviationBoundsUpperSampling upper_sampling = 5;
 
-  optional double lower_sampling = 6;
+  StandardDeviationBoundsLowerSampling lower_sampling = 6;
 }
 message StandardDeviationBoundsAsString {
   string upper = 1;
@@ -6520,17 +6621,59 @@ message StandardDeviationBoundsAsString {
 
   string lower_sampling = 6;
 }
+message StandardDeviationBoundsLower {
+  oneof standard_deviation_bounds_lower {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StandardDeviationBoundsLowerPopulation {
+  oneof standard_deviation_bounds_lower_population {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StandardDeviationBoundsLowerSampling {
+  oneof standard_deviation_bounds_lower_sampling {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StandardDeviationBoundsUpper {
+  oneof standard_deviation_bounds_upper {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StandardDeviationBoundsUpperPopulation {
+  oneof standard_deviation_bounds_upper_population {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StandardDeviationBoundsUpperSampling {
+  oneof standard_deviation_bounds_upper_sampling {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message StatsAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
   int64 count = 2;
 
-  double min = 3;
+  StatsAggregateBaseAllOfMin min = 3;
 
-  double max = 4;
+  StatsAggregateBaseAllOfMax max = 4;
 
-  double avg = 5;
+  StatsAggregateBaseAllOfAvg avg = 5;
 
   double sum = 6;
 
@@ -6548,11 +6691,11 @@ message StatsAggregateBase {
 
   int64 count = 2;
 
-  optional double min = 3;
+  StatsAggregateBaseAllOfMin min = 3;
 
-  optional double max = 4;
+  StatsAggregateBaseAllOfMax max = 4;
 
-  optional double avg = 5;
+  StatsAggregateBaseAllOfAvg avg = 5;
 
   double sum = 6;
 
@@ -6564,6 +6707,27 @@ message StatsAggregateBase {
 
   optional string sum_as_string = 10;
 }
+message StatsAggregateBaseAllOfAvg {
+  oneof stats_aggregate_base_all_of_avg {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StatsAggregateBaseAllOfMax {
+  oneof stats_aggregate_base_all_of_max {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
+message StatsAggregateBaseAllOfMin {
+  oneof stats_aggregate_base_all_of_min {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message StatsAggregation {
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   optional string field = 1;
@@ -6580,11 +6744,11 @@ message StatsBucketAggregate {
 
   int64 count = 2;
 
-  double min = 3;
+  StatsAggregateBaseAllOfMin min = 3;
 
-  double max = 4;
+  StatsAggregateBaseAllOfMax max = 4;
 
-  double avg = 5;
+  StatsAggregateBaseAllOfAvg avg = 5;
 
   double sum = 6;
 
@@ -6734,7 +6898,7 @@ message SumAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -6781,10 +6945,17 @@ message TTestAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  optional double value = 2;
+  TTestAggregateAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
+message TTestAggregateAllOfValue {
+  oneof t_test_aggregate_all_of_value {
+    double double = 1;
+
+    NullValue null_value = 2;
+  }
+}
 message TTestAggregation {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
@@ -6807,7 +6978,7 @@ message TermQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   FieldValue value = 3;
 
@@ -7054,7 +7225,7 @@ message TermsPartition {
 message TermsQuery {
   optional ObjectMap boost = 1;
 
-  optional ObjectMap underscore_name = 2;
+  optional ObjectMap x_name = 2;
 
   // Specifies the types of values used for filtering. Valid values are `default` and `bitmap`. Default is `default`.
   optional TermsQueryValueType value_type = 3;
@@ -7077,7 +7248,7 @@ message TermsSetQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // The path to a field or an array of paths. Some APIs support wildcards in the path, which allows you to select multiple fields.
   optional string minimum_should_match_field = 3;
@@ -7151,7 +7322,7 @@ message TopHitsAggregation {
   // If `true`, returns sequence number and primary term of the last modification of each hit.
   optional bool seq_no_primary_term = 14;
 
-  optional SourceConfig underscore_source = 15;
+  optional SourceConfig x_source = 15;
 }
 message TopLeftBottomRightGeoBounds {
   // The upper-left corner coordinates.
@@ -7188,7 +7359,7 @@ message TypeQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   string value = 3;
 }
@@ -7236,16 +7407,16 @@ message UpdateAction {
   // If the document does not already exist, the contents of `upsert` are inserted as a new document. If the document exists, the `script` is executed.
   optional ObjectMap upsert = 6;
 
-  optional SourceConfig underscore_source = 7;
+  optional SourceConfig x_source = 7;
 }
 message UpdateOperation {
   // The routing value for the document.
   optional string routing = 1;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 2;
+  optional string x_id = 2;
 
-  optional string underscore_index = 3;
+  optional string x_index = 3;
 
   optional int64 if_primary_term = 4;
 
@@ -7261,7 +7432,7 @@ message ValueCountAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -7376,7 +7547,7 @@ message WeightedAvgAggregate {
   // The custom metadata attached to a resource.
   optional ObjectMap meta = 1;
 
-  double value = 2;
+  SingleMetricAggregateBaseAllOfValue value = 2;
 
   optional string value_as_string = 3;
 }
@@ -7393,7 +7564,7 @@ message WildcardQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // Allows case insensitive matching of the pattern with the indexed field values when set to `true`. Default is `false` which means the case sensitivity of matching depends on the underlying field's mapping.
   optional bool case_insensitive = 3;
@@ -7416,7 +7587,7 @@ message WrapperQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   // A base64 encoded query. The binary data format can be any of JSON, YAML, CBOR or SMILE encodings
   string query = 3;
@@ -7426,9 +7597,9 @@ message WriteOperation {
   optional string routing = 1;
 
   // The unique identifier for a resource.
-  optional string underscore_id = 2;
+  optional string x_id = 2;
 
-  optional string underscore_index = 3;
+  optional string x_index = 3;
 
   // The pipeline ID for preprocessing documents. When the index has a default ingest pipeline specified, then setting the value to `_none` disables the default ingest pipeline for this request. When a final pipeline is configured, that pipeline will always run, regardless of the value of this parameter.
   optional string pipeline = 4;
@@ -7445,7 +7616,7 @@ message XyShapeQuery {
   // Floating point number used to decrease or increase the relevance scores of the query. Boost values are relative to the default value of 1.0. A boost value between 0 and 1.0 decreases the relevance score. A value greater than 1.0 increases the relevance score.
   optional float boost = 1;
 
-  optional string underscore_name = 2;
+  optional string x_name = 2;
 
   optional bool ignore_unmapped = 3;
 
diff --git a/protos/generated/services/default_service.proto b/protos/generated/services/default_service.proto
index 62510efb772..3bbc8870304 100644
--- a/protos/generated/services/default_service.proto
+++ b/protos/generated/services/default_service.proto
@@ -15,13 +15,13 @@ message BulkRequest {
   repeated BulkRequestInner bulk_request_inner = 2;
 
   // `true` or `false` to return the `_source` field or not, or a list of fields to return.
-  optional SourceConfigParam underscore_source = 3;
+  optional SourceConfigParam x_source = 3;
 
   // A comma-separated list of source fields to exclude from the response.
-  repeated string underscore_source_excludes = 4;
+  repeated string x_source_excludes = 4;
 
   // A comma-separated list of source fields to include in the response.
-  repeated string underscore_source_includes = 5;
+  repeated string x_source_includes = 5;
 
   // ID of the pipeline to use to preprocess incoming documents. If the index has a default ingest pipeline specified, then setting the value to `_none` disables the default ingest pipeline for this request. If a final pipeline is configured it will always run, regardless of the value of this parameter.
   optional string pipeline = 6;
@@ -70,13 +70,13 @@ message SearchRequest {
   repeated string index = 1;
 
   // Indicates which source fields are returned for matching documents. These fields are returned in the `hits._source` property of the search response. Valid values are: `true` to return the entire document source; `false` to not return the document source; `<string>` to return the source fields that are specified as a comma-separated list (supports wildcard (`*`) patterns).
-  optional SourceConfigParam underscore_source = 2;
+  optional SourceConfigParam x_source = 2;
 
   // A comma-separated list of source fields to exclude from the response. You can also use this parameter to exclude fields from the subset specified in `_source_includes` query parameter. If the `_source` parameter is `false`, this parameter is ignored.
-  repeated string underscore_source_excludes = 3;
+  repeated string x_source_excludes = 3;
 
   // A comma-separated list of source fields to include in the response. If this parameter is specified, only these source fields are returned. You can exclude fields from this subset using the `_source_excludes` query parameter. If the `_source` parameter is `false`, this parameter is ignored.
-  repeated string underscore_source_includes = 4;
+  repeated string x_source_includes = 4;
 
   // If `false`, the request returns an error if any wildcard expression, index alias, or `_all` value targets only missing or closed indexes. This behavior applies even if the request targets other open indexes. For example, a request targeting `foo*,bar*` returns an error if an index starts with `foo` but no index starts with `bar`.
   optional bool allow_no_indices = 5;