update java samples

samples/client/petstore/java/okhttp-gson-group-parameter/api/openapi.yaml

@@ -46,7 +46,7 @@ paths:
       tags:
       - pet
       x-content-type: application/json
-      x-accepts: application/json
+      x-accepts: "application/json,application/xml"
     put:
       description: ""
       operationId: updatePet
@@ -76,7 +76,7 @@ paths:
       tags:
       - pet
       x-content-type: application/json
-      x-accepts: application/json
+      x-accepts: "application/json,application/xml"
   /pet/findByStatus:
     get:
       description: Multiple status values can be provided with comma separated strings
@@ -120,7 +120,7 @@ paths:
       summary: Finds Pets by status
       tags:
       - pet
-      x-accepts: application/json
+      x-accepts: "application/json,application/xml"
   /pet/findByTags:
     get:
       deprecated: true
@@ -160,7 +160,7 @@ paths:
       summary: Finds Pets by tags
       tags:
       - pet
-      x-accepts: application/json
+      x-accepts: "application/json,application/xml"
   /pet/{petId}:
     delete:
       description: ""
@@ -225,7 +225,7 @@ paths:
       summary: Find pet by ID
       tags:
       - pet
-      x-accepts: application/json
+      x-accepts: "application/json,application/xml"
     post:
       description: ""
       operationId: updatePetWithForm