code: public synchronized void rollback() throws SQLException {
  
          checkClosed();
  
          try {
              sessionProxy.rollback(false);
          } catch (HsqlException e) {
              throw Util.sqlException(e);
          }
      }
docs: <!-- start generic documentation -->
  
  Undoes all changes made in the current transaction
  and releases any database locks currently held
  by this <code>Connection</code> object. This method should be
  used only when auto-commit mode has been disabled.
  
  <!-- end generic documentation -->
  <!-- start release-specific documentation -->
  <div class="ReleaseSpecificDocumentation">
  <h3>HSQLDB-Specific Information:</h3> <p>
  
  Starting with HSQLDB 1.7.2, savepoints are fully supported both
  in SQL and via the JDBC interface. <p>
  
  Using SQL, savepoints may be set, released and used in rollback
  as follows:
  
  <pre>
  SAVEPOINT &lt;savepoint-name&gt;
  RELEASE SAVEPOINT &lt;savepoint-name&gt;
  ROLLBACK TO SAVEPOINT &lt;savepoint-name&gt;
  </pre>
  
  </div> <!-- end release-specific documentation -->
  
  @exception SQLException if a database access error occurs,
  (JDBC4 Clarification:)
  this method is called while participating in a distributed transaction,
  this method is called on a closed connection or this
  <code>Connection</code> object is in auto-commit mode
  @see #setAutoCommit