private static String getExtensionPostfix(TypeElement interface_decl) { String interface_simple_name = interface_decl.getSimpleName().toString(); Extension extension_annotation = interface_decl.getAnnotation(Extension.class); if (extension_annotation == null) { int underscore_index = interface_simple_name.indexOf("_"); if (underscore_index != -1) { return interface_simple_name.substring(0, underscore_index); } else { return ""; } } else { return extension_annotation.postfix(); } }