code: @Override
      public ListPrincipalsResult listPrincipals(ListPrincipalsRequest request) {
          request = beforeClientExecution(request);
          return executeListPrincipals(request);
      }
docs: <p>
  Lists the principals with access to the specified resource.
  </p>
  
  @param listPrincipalsRequest
  @return Result of the ListPrincipals operation returned by the service.
  @throws MalformedArnException
  The format of an Amazon Resource Name (ARN) is not valid.
  @throws UnknownResourceException
  A specified resource was not found.
  @throws InvalidNextTokenException
  The specified value for NextToken is not valid.
  @throws InvalidParameterException
  A parameter is not valid.
  @throws ServerInternalException
  The service could not respond to the request due to an internal problem.
  @throws ServiceUnavailableException
  The service is not available.
  @sample AWSRAM.ListPrincipals
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/ram-2018-01-04/ListPrincipals" target="_top">AWS API
  Documentation</a>