presto-main/src/main/java/io/prestosql/metadata/PolymorphicScalarFunctionBuilder.java/PolymorphicScalarFunctionBuilder/ChoiceBuilder
class PolymorphicScalarFunctionBuilder:        private ChoiceBuilder(Class<?> clazz, Signature signature)
        {
            this.clazz = requireNonNull(clazz, "clazz is null");
            this.signature = requireNonNull(signature, "signature is null");
        }