presto-main/src/main/java/io/prestosql/operator/aggregation/multimapagg/MultimapAggregationStateFactory.java/MultimapAggregationStateFactory/MultimapAggregationStateFactory
class MultimapAggregationStateFactory:    public MultimapAggregationStateFactory(Type keyType, Type valueType, MultimapAggGroupImplementation implementation)
    {
        this.keyType = requireNonNull(keyType);
        this.valueType = requireNonNull(valueType);
        this.implementation = requireNonNull(implementation);
    }