code: void releaseSavepoint(final String savepointName) {
  		Savepoint savepoint = savepointMap.get(savepointName);
  
  		int pos = savepointNames.lastIndexOf(savepointName);
  		if (pos > -1) {
  			List<String> subList = savepointNames.subList(pos, savepointNames.size());
  			for (String name : subList) {
  				savepointMap.remove(name);
  			}
  			subList.clear();
  		}
  
  		if (savepoint != null && connection != null) {
  			try {
  				connection.releaseSavepoint(savepoint);
  			} catch (SQLException e) {
  				throw new UroborosqlSQLException(e);
  			}
  		}
  	}
docs: トランザクションから指定されたセーブポイントと以降のセーブポイントを削除します。
  
  <pre>
  この処理は{@link Connection#releaseSavepoint(java.sql.Savepoint)}の処理に依存します。
  </pre>
  
  @param savepointName セーブポイントの名前
  @throws SQLException SQL例外