code: @Override
      public OptionGroup modifyOptionGroup(ModifyOptionGroupRequest request) {
          request = beforeClientExecution(request);
          return executeModifyOptionGroup(request);
      }
docs: <p>
  Modifies an existing option group.
  </p>
  
  @param modifyOptionGroupRequest
  @return Result of the ModifyOptionGroup operation returned by the service.
  @throws InvalidOptionGroupStateException
  The option group isn't in the <i>available</i> state.
  @throws OptionGroupNotFoundException
  The specified option group could not be found.
  @sample AmazonRDS.ModifyOptionGroup
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/rds-2014-10-31/ModifyOptionGroup" target="_top">AWS API
  Documentation</a>