if (unionCorrespondingColumns.isEmpty()) {
throw Error.error(ErrorCode.X_42578);
}
leftQueryExpression.unionColumnMap = leftColumns.toArray();
rightQueryExpression.unionColumnMap = rightColumns.toArray();
} else {
leftQueryExpression.unionColumnMap =
new int[unionCorrespondingColumns.size()];
rightQueryExpression.unionColumnMap =
new int[unionCorrespondingColumns.size()];