Add AnnotationIntrospector.findPolymorphicTypeInfo()

Author: JooHyukKim

src/main/java/com/fasterxml/jackson/databind/AnnotationIntrospector.java

@@ -484,6 +484,20 @@ public VisibilityChecker<?> findAutoDetectVisibility(AnnotatedClass ac,
     /**********************************************************
     */
 
+    /**
+     * Method for checking whether given Class or Property Accessor specifies
+     * polymorphic type-handling information, to indicate need for polymorphic
+     * handling.
+     *
+     * @param config Effective mapper configuration in use
+     * @param ann Annotated entity to introspect
+     *
+     * @since 2.16 (backported from Jackson 3.0)
+     */
+    public JsonTypeInfo.Value findPolymorphicTypeInfo(MapperConfig<?> config, Annotated ann) {
+        return null;
+    }
+
     /**
      * Method for checking if given class has annotations that indicate
      * that specific type resolver is to be used for handling instances.

src/main/java/com/fasterxml/jackson/databind/introspect/AnnotationIntrospectorPair.java

@@ -231,6 +231,19 @@ public VisibilityChecker<?> findAutoDetectVisibility(AnnotatedClass ac,
     /******************************************************
      */
 
+    /**
+     * @since 2.16 (backported from Jackson 3.0)
+     */
+    @Override
+    public JsonTypeInfo.Value findPolymorphicTypeInfo(MapperConfig<?> config, Annotated ann)
+    {
+        JsonTypeInfo.Value v = _primary.findPolymorphicTypeInfo(config, ann);
+        if (v == null) {
+            v = _secondary.findPolymorphicTypeInfo(config, ann);
+        }
+        return v;
+    }
+
     @Override
     public TypeResolverBuilder<?> findTypeResolver(MapperConfig<?> config,
             AnnotatedClass ac, JavaType baseType)

src/main/java/com/fasterxml/jackson/databind/introspect/JacksonAnnotationIntrospector.java

@@ -593,6 +593,16 @@ public PropertyName findRenameByField(MapperConfig<?> config,
     /**********************************************************
      */
 
+    /**
+     * @since 2.16 (backported from Jackson 3.0)
+     */
+    @Override
+    public JsonTypeInfo.Value findPolymorphicTypeInfo(MapperConfig<?> config, Annotated ann)
+    {
+        JsonTypeInfo t = _findAnnotation(ann, JsonTypeInfo.class);
+        return (t == null) ? null : JsonTypeInfo.Value.from(t);
+    }
+
     @Override
     public TypeResolverBuilder<?> findTypeResolver(MapperConfig<?> config,
             AnnotatedClass ac, JavaType baseType)