public <T> List<T> executeWithKeys(Class<T> type) {
        return executeWithKeys(type, null);
    }
Execute the clause and return the generated key with the type of the
given path. If no rows were created, or the referenced column is not a
generated key, null is returned. Otherwise, the key of the first row is
returned.

@param <T>
@param path path for key
@return generated keys
querydsl-sql/src/main/java/com/querydsl/sql/dml/AbstractSQLInsertClause.java