core/src/main/java/com/orientechnologies/orient/core/Orient.java
public void addShutdownHandler(OShutdownHandler shutdownHandler) {
    engineLock.writeLock().lock();
    try {
      shutdownHandlers.add(shutdownHandler);
    } finally {
      engineLock.writeLock().unlock();
    }
  }
public void addShutdownHandler(OShutdownHandler shutdownHandler) {
    engineLock.writeLock().lock();
    try {
      shutdownHandlers.add(shutdownHandler);
    } finally {
      engineLock.writeLock().unlock();
    }
  }
public void addShutdownHandler ( OShutdownHandler shutdownHandler ) { engineLock . writeLock ( ) . lock ( ) ; try { shutdownHandlers . add ( shutdownHandler ) ; } finally { engineLock . writeLock ( ) . unlock ( ) ; } }
Add handler which will be executed during {@link #shutdown()} call.

@param shutdownHandler Shutdown handler instance.
Add handler which will be executed during { @link #shutdown () } call .