presto-main/src/main/java/io/prestosql/operator/scalar/CastFromUnknownOperator.java/CastFromUnknownOperator/handleNonNull
class CastFromUnknownOperator:    @UsedByGeneratedCode
    public static Object handleNonNull(boolean arg)
    {
        throw new IllegalArgumentException("value of unknown type should always be null");
    }