code: protected Response error(String input, Exception e) {
          return Response.status(getErrorStatus()).entity(errorMessage(input, e)).type(mediaType()).build();
      }
docs: Given a string representation which was unable to be parsed and the exception thrown, produce
  a {@link javax.ws.rs.core.Response} to be sent to the client.
  
  By default, generates a {@code 400 Bad Request} with a plain text entity generated by
  {@link #errorMessage(String, Exception)}.
  
  @param input the raw input value
  @param e the exception thrown while parsing {@code input}
  @return the {@link javax.ws.rs.core.Response} to be sent to the client