presto-main/src/main/java/io/prestosql/operator/aggregation/AccumulatorCompiler.java/AccumulatorCompiler/generateAccumulatorFactoryBinder
class AccumulatorCompiler:    public static GenericAccumulatorFactoryBinder generateAccumulatorFactoryBinder(AggregationMetadata metadata, DynamicClassLoader classLoader)
    {
        Class<? extends Accumulator> accumulatorClass = generateAccumulatorClass(
                Accumulator.class,
                metadata,
                classLoader);

        Class<? extends GroupedAccumulator> groupedAccumulatorClass = generateAccumulatorClass(
                GroupedAccumulator.class,
                metadata,
                classLoader);

        return new GenericAccumulatorFactoryBinder(
                metadata.getAccumulatorStateDescriptors(),
                accumulatorClass,
                metadata.getRemoveInputFunction().isPresent(),
                groupedAccumulatorClass);
    }