#18058 Fix the Java generator to generate valid @RequestMappings where the produce field takes list of string parameters instead of a single comma-separated string (#18092)

* #18058 Fix AbstractJavaCodegen.getAccepts() so it returns a String array instead of a comma-separated string, and fixed api.mustache so the @RequestMapping annotation generated produces for x-accepts as a parameter list instead of a (single) string.

* #18058 Updated test case to accept a string array instead of a comma-separated list.

* #18058 Reverted changes on imported compared to the main branch.

* #18058 getAccepts() is now hybrid, and can return both a single String or a String[].

* #18058 Rolled back the hybrid getAccepts(), so it only returns a String array.

* #18058 Updated mustache files to cope with vendorExtensions.x-accepts being a string array instead of a comma-separated string.

* #18058 Generated new sample files with by running `./bin/generate-samples.sh ./bin/configs/*.yaml`

* #18058 Optimization of getAccepts()

* #18058 Regenerated scripts that got broken after resolving conflicts on GitHub

* #18058 Fixed introduced issue with api.mustache causing a redundant accept with @HttpExchange with the PetApi.java, StoreApi.java, and UserApi.java.

samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8/api/openapi.yaml

@@ -51,7 +51,8 @@ paths:
       summary: Use both API keys
       tags:
       - usage
-      x-accepts: application/json
+      x-accepts:
+      - application/json
   /any:
     get:
       description: Use any API key
@@ -69,7 +70,8 @@ paths:
       summary: Use any API key
       tags:
       - usage
-      x-accepts: application/json
+      x-accepts:
+      - application/json
   /query:
     get:
       description: Use API key in query
@@ -86,7 +88,8 @@ paths:
       summary: Use API key in query
       tags:
       - usage
-      x-accepts: application/json
+      x-accepts:
+      - application/json
   /header:
     get:
       description: Use API key in header
@@ -103,7 +106,8 @@ paths:
       summary: Use API key in header
       tags:
       - usage
-      x-accepts: application/json
+      x-accepts:
+      - application/json
 components:
   schemas: {}
   securitySchemes: