< A extends SimpleAggregator , T > Class < ? extends Number > getAggregatorUnit ( Class < A > klass ) { try { A aggregator = ( A ) CONSTRUCTORS . get ( klass ) . newInstance ( "forAggregatorTypeDiscoveryOnly" ) ; return aggregator . getValueType ( ) ; } catch ( Exception ex ) { throw new RuntimeException ( ex ) ; } }
Returns the unit type of an aggregator value . Typically Long or Double .