[Java][Jersey2] Add JsonTypeName annotation (#6551)

* Mustache template should use invokerPackage tag to generate import

* add JsonSubTypes annotation to handle scenario when OAS name has special characters

* add JsonSubTypes annotation to handle scenario when OAS name has special characters. Add unit test

* run sample scripts

* fix unit test

* run sample scripts

* add minimal openapi document to show issue with special characters and discriminators

* Add 'isClassnameSanitized' tag

* Add 'isClassnameSanitized' tag

* Add 'isClassnameSanitized' tag

* Add 'isClassnameSanitized' tag

* Add 'isClassnameSanitized' tag

* Add 'isClassnameSanitized' tag

* Add unit tests for unmarshaling of discriminators with special characters

* Add unit tests for unmarshaling of discriminators with special characters

* use JsonTypeName

Co-authored-by: Vikrant Balyan (vvb) <vvb@cisco.com>
Co-authored-by: William Cheng <wing328hk@gmail.com>

samples/openapi3/client/petstore/java/jersey2-java8-special-characters/api/openapi.yaml

@@ -0,0 +1,53 @@
+openapi: 3.0.3
+info:
+  description: test
+  title: test
+  version: 1.0.0
+servers:
+- url: /
+paths:
+  /test:
+    post:
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/MySchemaName._-Characters'
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/MySchemaName._-Characters'
+          description: the response
+      x-contentType: application/json
+      x-accepts: application/json
+components:
+  schemas:
+    Parent:
+      discriminator:
+        propertyName: objectType
+      properties:
+        objectType:
+          type: string
+    ChildSchema:
+      allOf:
+      - $ref: '#/components/schemas/Parent'
+      - $ref: '#/components/schemas/ChildSchema_allOf'
+      description: A schema that does not have any special character.
+    MySchemaName._-Characters:
+      allOf:
+      - $ref: '#/components/schemas/Parent'
+      - $ref: '#/components/schemas/MySchemaName___Characters_allOf'
+      description: A schema name that has letters, numbers, punctuation and non-ASCII
+        characters. The sanitization rules should make it possible to generate a language-specific
+        classname with allowed characters in that programming language.
+    ChildSchema_allOf:
+      properties:
+        prop1:
+          type: string
+    MySchemaName___Characters_allOf:
+      properties:
+        prop2:
+          type: string
+