refactor: address review comments for JsonSchema generation

- Apply LY OSS formatting and improve readability for JacksonPolymorphismTypeInfoProvider.

- Update DiscriminatorInfo Javadoc to use FQCN for clarity.

- Remove unused fields and imports in JsonSchemaGenerator.

- Fix Checkstyle errors regarding operator wrapping in JsonSchemaGenerator.

Author: YoungHoney

core/src/main/java/com/linecorp/armeria/internal/server/docs/JacksonPolymorphismTypeInfoProvider.java

@@ -101,25 +101,25 @@ public DescriptiveTypeInfo newDescriptiveTypeInfo(Object typeDescriptor) {
         final DiscriminatorInfo discriminator = DiscriminatorInfo.of(propertyName, mapping);
 
         final List<TypeSignature> oneOf = Arrays.stream(jsonSubTypes.value())
-                .map(subType -> TypeSignature.ofStruct(subType.value()))
-                .collect(toImmutableList());
+                                                .map(subType -> TypeSignature.ofStruct(subType.value()))
+                                                .collect(toImmutableList());
 
         final JavaType javaType = mapper.constructType(clazz);
         final BeanDescription description = mapper.getSerializationConfig().introspect(javaType);
         final List<BeanPropertyDefinition> properties = description.findProperties();
 
         final List<FieldInfo> fields = properties.stream()
-                .map(prop -> FieldInfo.of(prop.getName(),
-                        toTypeSignature(
-                                prop.getPrimaryType())))
-                .collect(toImmutableList());
+                                                 .map(prop -> FieldInfo.of(prop.getName(),
+                                                                           toTypeSignature(
+                                                                                   prop.getPrimaryType())))
+                                                 .collect(toImmutableList());
 
         final Description classDescription = clazz.getAnnotation(Description.class);
 
         final DescriptionInfo descriptionInfo = classDescription == null ? DescriptionInfo.empty()
-                : DescriptionInfo.from(classDescription);
+                                                                         : DescriptionInfo.from(
+                classDescription);
 
-        return new StructInfo(clazz.getName(), null, fields,
-                descriptionInfo, oneOf, discriminator);
+        return new StructInfo(clazz.getName(), null, fields, descriptionInfo, oneOf, discriminator);
     }
 }

core/src/main/java/com/linecorp/armeria/server/docs/DiscriminatorInfo.java

@@ -39,9 +39,6 @@
 @UnstableApi
 public final class DiscriminatorInfo {
 
-    private final String propertyName;
-    private final Map<String, String> mapping;
-
     /**
      * Creates a new {@link DiscriminatorInfo} with {@code propertyName}, the name
      * of the property
@@ -52,6 +49,9 @@ public static DiscriminatorInfo of(String propertyName, Map<String, String> mapp
         return new DiscriminatorInfo(propertyName, mapping);
     }
 
+    private final String propertyName;
+    private final Map<String, String> mapping;
+
     /**
      * Creates a new instance.
      */
@@ -74,7 +74,7 @@ public String propertyName() {
      * The keys are the values that appear in the {@link #propertyName()} field, and
      * the values are
      * the schema definitions to use for that value (e.g.,
-     * {@code "#/$defs/models/Cat"}).
+     * {@code "#/$defs/models/com.linecorp.armeria.Cat"}).
      */
     @JsonProperty
     public Map<String, String> mapping() {
@@ -101,6 +101,6 @@ public int hashCode() {
     @Override
     public String toString() {
         return MoreObjects.toStringHelper(this).add("propertyName", propertyName).add("mapping", mapping)
-                .toString();
+                          .toString();
     }
 }

core/src/main/java/com/linecorp/armeria/server/docs/JsonSchemaGenerator.java

@@ -15,20 +15,17 @@
  */
 package com.linecorp.armeria.server.docs;
 
-import static com.google.common.collect.ImmutableMap.toImmutableMap;
 import static java.util.Objects.requireNonNull;
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.function.Function;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ArrayNode;
 import com.fasterxml.jackson.databind.node.ObjectNode;
-import com.google.common.collect.ImmutableMap;
 
 import com.linecorp.armeria.internal.common.JacksonUtil;
 
@@ -42,28 +39,13 @@ final class JsonSchemaGenerator {
     private static final ObjectMapper mapper = JacksonUtil.newDefaultObjectMapper();
 
     private final ServiceSpecification serviceSpecification;
-    private final Map<String, StructInfo> structs;
-    private final Map<String, EnumInfo> enums;
     private final Map<String, DiscriminatorInfo> polymorphismToBase;
     private final Map<String, DescriptionInfo> docStrings;
 
     private JsonSchemaGenerator(ServiceSpecification serviceSpecification) {
         this.serviceSpecification = requireNonNull(serviceSpecification, "serviceSpecification");
         docStrings = serviceSpecification.docStrings();
 
-        final ImmutableMap.Builder<String, StructInfo> structsBuilder = ImmutableMap
-                .builderWithExpectedSize(serviceSpecification.structs().size());
-        for (final StructInfo structInfo : serviceSpecification.structs()) {
-            structsBuilder.put(structInfo.name(), structInfo);
-            if (structInfo.alias() != null) {
-                structsBuilder.put(structInfo.alias(), structInfo);
-            }
-        }
-        structs = structsBuilder.build();
-
-        enums = serviceSpecification.enums().stream()
-                .collect(toImmutableMap(EnumInfo::name, Function.identity()));
-
         // Pre-compute mappings from subtype to its base type's DiscriminatorInfo
         final Map<String, String> nameToAlias = new HashMap<>();
         for (final StructInfo struct : serviceSpecification.structs()) {
@@ -146,6 +128,19 @@ private static String getSchemaType(TypeSignature typeSignature) {
         }
     }
 
+    private static ObjectNode generateEnumDefinition(EnumInfo enumInfo) {
+        final ObjectNode schemaNode = mapper.createObjectNode();
+        schemaNode.put("type", "string");
+        final String docString = enumInfo.descriptionInfo().docString();
+        if (!docString.isEmpty()) {
+            schemaNode.put("description", docString);
+        }
+        final ArrayNode enumValues = mapper.createArrayNode();
+        enumInfo.values().forEach(value -> enumValues.add(value.name()));
+        schemaNode.set("enum", enumValues);
+        return schemaNode;
+    }
+
     private ObjectNode doGenerate() {
         final ObjectNode root = mapper.createObjectNode();
         if (serviceSpecification.services().isEmpty()) {
@@ -252,19 +247,6 @@ private ObjectNode generateStructDefinition(StructInfo structInfo) {
         return schemaNode;
     }
 
-    private static ObjectNode generateEnumDefinition(EnumInfo enumInfo) {
-        final ObjectNode schemaNode = mapper.createObjectNode();
-        schemaNode.put("type", "string");
-        final String docString = enumInfo.descriptionInfo().docString();
-        if (!docString.isEmpty()) {
-            schemaNode.put("description", docString);
-        }
-        final ArrayNode enumValues = mapper.createArrayNode();
-        enumInfo.values().forEach(value -> enumValues.add(value.name()));
-        schemaNode.set("enum", enumValues);
-        return schemaNode;
-    }
-
     private ObjectNode generateMethodSchema(String serviceName, MethodInfo methodInfo) {
         final ObjectNode root = mapper.createObjectNode();
         root.put("$id", methodInfo.id());
@@ -322,13 +304,13 @@ private ObjectNode generateFieldSchema(FieldInfo field) {
         }
 
         if (typeSignature.type() == TypeSignatureType.STRUCT ||
-                typeSignature.type() == TypeSignatureType.ENUM) {
+            typeSignature.type() == TypeSignatureType.ENUM) {
             fieldNode.put("$ref", "#/$defs/models/" + typeSignature.name());
             return fieldNode;
         }
 
         if (typeSignature.type() == TypeSignatureType.OPTIONAL ||
-                typeSignature.type() == TypeSignatureType.CONTAINER) {
+            typeSignature.type() == TypeSignatureType.CONTAINER) {
             final TypeSignature inner = ((ContainerTypeSignature) typeSignature).typeParameters().get(0);
             final ObjectNode innerNode = generateFieldSchema(FieldInfo.of("", inner));
             if (!docString.isEmpty()) {
@@ -349,7 +331,7 @@ private ObjectNode generateFieldSchema(FieldInfo field) {
             case MAP: {
                 final TypeSignature valueType = ((MapTypeSignature) typeSignature).valueTypeSignature();
                 fieldNode.set("additionalProperties",
-                        generateFieldSchema(FieldInfo.of("", valueType)));
+                              generateFieldSchema(FieldInfo.of("", valueType)));
                 break;
             }
             default: