presto-main/src/main/java/io/prestosql/operator/aggregation/RealAverageAggregation.java/RealAverageAggregation/createInputParameterMetadata
class RealAverageAggregation:    private static List<ParameterMetadata> createInputParameterMetadata(Type value)
    {
        return ImmutableList.of(new ParameterMetadata(STATE), new ParameterMetadata(BLOCK_INPUT_CHANNEL, value), new ParameterMetadata(BLOCK_INDEX));
    }