presto-spi/src/main/java/io/prestosql/spi/type/RowType.java/RowType/checkElementNotNull
class RowType:    private static void checkElementNotNull(boolean isNull)
    {
        if (isNull) {
            throw new PrestoException(StandardErrorCode.NOT_SUPPORTED, "ROW comparison not supported for fields with null elements");
        }
    }