@SuppressWarnings("unchecked") public B subAggregation(AbstractAggregationBuilder aggregation){
  if (aggregations == null) {
    aggregations=new ArrayList<>();
  }
  aggregations.add(aggregation);
  return (B)this;
}

@ SuppressWarnings ( "unchecked" ) public B subAggregation ( AbstractAggregationBuilder aggregation ) { if ( aggregations == null ) { aggregations = new ArrayList < > ( ) ; } aggregations . add ( aggregation ) ; return ( B ) this ; }
add a sub get to this bucket get .
