Add new JsonTypeInfo.Id.SIMPLE_NAME (#234)

src/main/java/com/fasterxml/jackson/annotation/JsonTypeInfo.java

@@ -119,6 +119,23 @@ public enum Id {
          */
         NAME("@type"),
 
+        /**
+         * Means that the simple name of the Java class, equivalent to the value returned by {@link Class#getSimpleName()},
+         * is used as the default type identifier, unless explicit name is specified by annotation {@link JsonTypeName}.
+         *<br>
+         * For instance: 
+         * <ul>
+         *     <li>For a class "com.example.MyClass", only "MyClass" is used.</li>
+         *     <li>For an inner class "com.example.MyClass$Inner", only "Inner" is used.</li>
+         * </ul>
+         * <b>Note:</b> This approach reduces verbosity but requires the simple names to be unique 
+         * to avoid conflicts. If multiple classes share the same simple name, <b>the last declared one</b>
+         * will be used. This approach should be used with careful consideration of your type hierarchy.
+         *
+         * @since 2.16
+         */
+        SIMPLE_NAME("@type"),
+
         /**
          * Means that no serialized typing-property is used. Types are <i>deduced</i> based
          * on the fields available. Deduction is limited to the <i>names</i> of fields

src/test/java/com/fasterxml/jackson/annotation/JsonTypeInfoTest.java

@@ -61,6 +61,8 @@ public void testMutators() throws Exception
         assertSame(v, v.withIdType(JsonTypeInfo.Id.CLASS));
         JsonTypeInfo.Value v2 = v.withIdType(JsonTypeInfo.Id.MINIMAL_CLASS);
         assertEquals(JsonTypeInfo.Id.MINIMAL_CLASS, v2.getIdType());
+        JsonTypeInfo.Value v3 = v.withIdType(JsonTypeInfo.Id.SIMPLE_NAME);
+        assertEquals(JsonTypeInfo.Id.SIMPLE_NAME, v3.getIdType());
 
         assertEquals(JsonTypeInfo.As.PROPERTY, v.getInclusionType());
         assertSame(v, v.withInclusionType(JsonTypeInfo.As.PROPERTY));