public PercolateSourceBuilder addAggregation(AbstractAggregationBuilder aggregationBuilder){
  if (aggregations == null) {
    aggregations=new ArrayList<>();
  }
  aggregations.add(aggregationBuilder);
  return this;
}

public PercolateSourceBuilder addAggregation ( AbstractAggregationBuilder aggregationBuilder ) { if ( aggregations == null ) { aggregations = new ArrayList < > ( ) ; } aggregations . add ( aggregationBuilder ) ; return this ; }
add an aggregation definition .
