presto-main/src/main/java/io/prestosql/metadata/PolymorphicScalarFunction.java/PolymorphicScalarFunction/PolymorphicScalarFunction
class PolymorphicScalarFunction:    PolymorphicScalarFunction(FunctionMetadata functionMetadata, List<PolymorphicScalarFunctionChoice> choices)
    {
        super(functionMetadata);
        this.choices = requireNonNull(choices, "choices is null");
    }