code: @Override
      public DescribeReservedElasticsearchInstancesResult describeReservedElasticsearchInstances(DescribeReservedElasticsearchInstancesRequest request) {
          request = beforeClientExecution(request);
          return executeDescribeReservedElasticsearchInstances(request);
      }
docs: <p>
  Returns information about reserved Elasticsearch instances for this account.
  </p>
  
  @param describeReservedElasticsearchInstancesRequest
  Container for parameters to <code>DescribeReservedElasticsearchInstances</code>
  @return Result of the DescribeReservedElasticsearchInstances operation returned by the service.
  @throws ResourceNotFoundException
  An exception for accessing or deleting a resource that does not exist. Gives http status code of 400.
  @throws InternalException
  The request processing has failed because of an unknown error, exception or failure (the failure is
  internal to the service) . Gives http status code of 500.
  @throws ValidationException
  An exception for missing / invalid input fields. Gives http status code of 400.
  @throws DisabledOperationException
  An error occured because the client wanted to access a not supported operation. Gives http status code of
  409.
  @sample AWSElasticsearch.DescribeReservedElasticsearchInstances