code: @Override
      public ListFunctionDefinitionsResult listFunctionDefinitions(ListFunctionDefinitionsRequest request) {
          request = beforeClientExecution(request);
          return executeListFunctionDefinitions(request);
      }
docs: Retrieves a list of Lambda function definitions.
  
  @param listFunctionDefinitionsRequest
  @return Result of the ListFunctionDefinitions operation returned by the service.
  @sample AWSGreengrass.ListFunctionDefinitions
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/greengrass-2017-06-07/ListFunctionDefinitions"
  target="_top">AWS API Documentation</a>