code: @Override
      public DescribeDBParameterGroupsResult describeDBParameterGroups(DescribeDBParameterGroupsRequest request) {
          request = beforeClientExecution(request);
          return executeDescribeDBParameterGroups(request);
      }
docs: <p>
  Returns a list of <code>DBParameterGroup</code> descriptions. If a <code>DBParameterGroupName</code> is
  specified, the list will contain only the description of the specified DB parameter group.
  </p>
  
  @param describeDBParameterGroupsRequest
  @return Result of the DescribeDBParameterGroups operation returned by the service.
  @throws DBParameterGroupNotFoundException
  <i>DBParameterGroupName</i> does not refer to an existing DB parameter group.
  @sample AmazonNeptune.DescribeDBParameterGroups
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/neptune-2014-10-31/DescribeDBParameterGroups"
  target="_top">AWS API Documentation</a>