java supports inheritance

as per #1015 (and #946) this is now optional and disabled by default.
this results in extra unnecessary code, masking fields in some cases, and
breaks code generated for jax-rs in certain cases (enums with inheritance).

Author: ahgittin

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java

@@ -22,6 +22,7 @@ public class JavaClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     public JavaClientCodegen() {
         super();
+        supportsInheritance = true;
         outputFolder = "generated-code/java";
         modelTemplateFiles.put("model.mustache", ".java");
         apiTemplateFiles.put("api.mustache", ".java");