code: @Override
      public ListDocumentVersionsResult listDocumentVersions(ListDocumentVersionsRequest request) {
          request = beforeClientExecution(request);
          return executeListDocumentVersions(request);
      }
docs: <p>
  List all versions for a document.
  </p>
  
  @param listDocumentVersionsRequest
  @return Result of the ListDocumentVersions operation returned by the service.
  @throws InternalServerErrorException
  An error occurred on the server side.
  @throws InvalidNextTokenException
  The specified token is not valid.
  @throws InvalidDocumentException
  The specified document does not exist.
  @sample AWSSimpleSystemsManagement.ListDocumentVersions
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/ssm-2014-11-06/ListDocumentVersions" target="_top">AWS API
  Documentation</a>