[Java] rename x-contentType to x-content-type (#11895)

* rename x-contentType to x-content-type

* undo changes

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

@@ -68,7 +68,7 @@ paths:
       summary: Add a new pet to the store
       tags:
       - pet
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
     put:
       description: ""
@@ -90,7 +90,7 @@ paths:
       summary: Update an existing pet
       tags:
       - pet
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
     servers:
     - url: http://petstore.swagger.io/v2
@@ -284,7 +284,7 @@ paths:
       summary: Updates a pet in the store with form data
       tags:
       - pet
-      x-contentType: application/x-www-form-urlencoded
+      x-content-type: application/x-www-form-urlencoded
       x-accepts: application/json
   /pet/{petId}/uploadImage:
     post:
@@ -328,7 +328,7 @@ paths:
       summary: uploads an image
       tags:
       - pet
-      x-contentType: multipart/form-data
+      x-content-type: multipart/form-data
       x-accepts: application/json
   /store/inventory:
     get:
@@ -376,7 +376,7 @@ paths:
       summary: Place an order for a pet
       tags:
       - store
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /store/order/{order_id}:
     delete:
@@ -452,7 +452,7 @@ paths:
       summary: Create user
       tags:
       - user
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /user/createWithArray:
     post:
@@ -466,7 +466,7 @@ paths:
       summary: Creates list of users with given input array
       tags:
       - user
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /user/createWithList:
     post:
@@ -480,7 +480,7 @@ paths:
       summary: Creates list of users with given input array
       tags:
       - user
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /user/login:
     get:
@@ -624,7 +624,7 @@ paths:
       summary: Updated user
       tags:
       - user
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /fake_classname_test:
     patch:
@@ -644,7 +644,7 @@ paths:
       summary: To test class name in snake case
       tags:
       - fake_classname_tags 123#$%^
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /fake:
     delete:
@@ -825,7 +825,7 @@ paths:
       summary: To test enum parameters
       tags:
       - fake
-      x-contentType: application/x-www-form-urlencoded
+      x-content-type: application/x-www-form-urlencoded
       x-accepts: application/json
     patch:
       description: To test "client" model
@@ -842,7 +842,7 @@ paths:
       summary: To test "client" model
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
     post:
       description: |
@@ -943,7 +943,7 @@ paths:
         가짜 엔드 포인트
       tags:
       - fake
-      x-contentType: application/x-www-form-urlencoded
+      x-content-type: application/x-www-form-urlencoded
       x-accepts: application/json
   /fake/outer/number:
     post:
@@ -964,7 +964,7 @@ paths:
           description: Output number
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: '*/*'
   /fake/outer/string:
     post:
@@ -985,7 +985,7 @@ paths:
           description: Output string
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: '*/*'
   /fake/outer/boolean:
     post:
@@ -1006,7 +1006,7 @@ paths:
           description: Output boolean
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: '*/*'
   /fake/outer/composite:
     post:
@@ -1027,7 +1027,7 @@ paths:
           description: Output composite
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: '*/*'
   /fake/jsonFormData:
     get:
@@ -1055,7 +1055,7 @@ paths:
       summary: test json serialization of form data
       tags:
       - fake
-      x-contentType: application/x-www-form-urlencoded
+      x-content-type: application/x-www-form-urlencoded
       x-accepts: application/json
   /fake/inline-additionalProperties:
     post:
@@ -1076,7 +1076,7 @@ paths:
       summary: test inline additionalProperties
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /fake/body-with-query-params:
     put:
@@ -1100,7 +1100,7 @@ paths:
           description: Success
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /another-fake/dummy:
     patch:
@@ -1118,7 +1118,7 @@ paths:
       summary: To test special tags
       tags:
       - $another-fake?
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /fake/body-with-file-schema:
     put:
@@ -1136,7 +1136,7 @@ paths:
           description: Success
       tags:
       - fake
-      x-contentType: application/json
+      x-content-type: application/json
       x-accepts: application/json
   /fake/test-query-parameters:
     put:
@@ -1238,7 +1238,7 @@ paths:
       summary: uploads an image (required)
       tags:
       - pet
-      x-contentType: multipart/form-data
+      x-content-type: multipart/form-data
       x-accepts: application/json
   /fake/health:
     get: