presto-main/src/main/java/io/prestosql/operator/aggregation/multimapagg/MultimapAggregationFunction.java/MultimapAggregationFunction/MultimapAggregationFunction
class MultimapAggregationFunction:    public MultimapAggregationFunction(MultimapAggGroupImplementation groupMode)
    {
        super(
                new FunctionMetadata(
                        new Signature(
                                NAME,
                                ImmutableList.of(comparableTypeParameter("K"), typeVariable("V")),
                                ImmutableList.of(),
                                mapType(new TypeSignature("K"), arrayType(new TypeSignature("V"))),
                                ImmutableList.of(new TypeSignature("K"), new TypeSignature("V")),
                                false),
                        true,
                        ImmutableList.of(
                                new FunctionArgumentDefinition(false),
                                new FunctionArgumentDefinition(true)),
                        false,
                        true,
                        "Aggregates all the rows (key/value pairs) into a single multimap",
                        AGGREGATE),
                true,
                true);
        this.groupMode = groupMode;
    }