fix post process file type (#18519)

Author: mathewab

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -8139,7 +8139,7 @@ protected void setParameterNullable(CodegenParameter parameter, CodegenProperty
 
     /**
      * Post-process the auto-generated file, e.g. using go-fmt to format the Go code. The file type can be "model-test",
-     * "model-doc", "model", "api", "api-test", "api-doc", "supporting-mustache", "supporting-common",
+     * "model-doc", "model", "api", "api-test", "api-doc", "supporting-file",
      * "openapi-generator-ignore", "openapi-generator-version"
      * <p>
      * TODO: store these values in enum instead

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java

@@ -966,7 +966,7 @@ public void postProcessFile(File file, String fileType) {
         // only process the following type (or we can simply rely on the file extension to check if it's a Go file)
         Set<String> supportedFileType = new HashSet<>(
                 Arrays.asList(
-                        "supporting-mustache",
+                        "supporting-file",
                         "model-test",
                         "model",
                         "api-test",