@Override
    public long execute() {
        if (configuration.getTemplates().isNativeMerge()) {
            return executeNativeMerge();
        } else {
            return executeCompositeMerge();
        }
    }
Execute the clause and return the generated keys as a ResultSet

@return result set with generated keys
querydsl-sql/src/main/java/com/querydsl/sql/dml/SQLMergeClause.java