Fix review comments

Author: PingLiuPing

velox/connectors/hive/iceberg/IcebergDataSink.cpp

@@ -65,6 +65,21 @@ folly::dynamic extractPartitionValue<TypeKind::TIMESTAMP>(
   return timestamp.toMicros();
 }
 
+class IcebergInsertFileNameGenerator : public FileNameGenerator {
+ public:
+  IcebergInsertFileNameGenerator() {}
+
+  std::pair<std::string, std::string> gen(
+      std::optional<uint32_t> bucketId,
+      const std::shared_ptr<const HiveInsertTableHandle> insertTableHandle,
+      const ConnectorQueryCtx& connectorQueryCtx,
+      bool commitRequired) const override;
+
+  folly::dynamic serialize() const override;
+
+  std::string toString() const override;
+};
+
 } // namespace
 
 std::pair<std::string, std::string> IcebergInsertFileNameGenerator::gen(

velox/connectors/hive/iceberg/IcebergDataSink.h

@@ -22,21 +22,6 @@
 
 namespace facebook::velox::connector::hive::iceberg {
 
-class IcebergInsertFileNameGenerator : public FileNameGenerator {
- public:
-  IcebergInsertFileNameGenerator() {}
-
-  std::pair<std::string, std::string> gen(
-      std::optional<uint32_t> bucketId,
-      const std::shared_ptr<const HiveInsertTableHandle> insertTableHandle,
-      const ConnectorQueryCtx& connectorQueryCtx,
-      bool commitRequired) const override;
-
-  folly::dynamic serialize() const override;
-
-  std::string toString() const override;
-};
-
 // Represents a request for Iceberg write.
 class IcebergInsertTableHandle final : public HiveInsertTableHandle {
  public:

velox/connectors/hive/iceberg/IcebergPartitionIdGenerator.cpp

@@ -23,16 +23,6 @@ namespace facebook::velox::connector::hive::iceberg {
 
 namespace {
 
-std::string toLower(const std::string& data) {
-  std::string ret;
-  ret.reserve(data.size());
-  std::transform(
-      data.begin(), data.end(), std::back_inserter(ret), [](auto& c) {
-        return std::tolower(c);
-      });
-  return ret;
-}
-
 template <TypeKind Kind>
 std::pair<std::string, std::string> makePartitionKeyValueString(
     const BaseVector* partitionVector,