code: public static InvocationResponse error(Throwable t) {
  		InvocationResponse resp = new InvocationResponse(ERROR);
  		resp.errorMessage = t.getClass().getName() + ":" + t.getLocalizedMessage();
  		return resp;
  	}
docs: Creates a new {@link InvocationResponse} to hold the error that occurred
  during the execution of the service.
  
  @param t
  - the throwable that caused the error.
  @return the invocation request.