code: public final boolean unregisterCloseable(C closeable) {
  
  		if (null == closeable) {
  			return false;
  		}
  
  		synchronized (getSynchronizationLock()) {
  			return doUnRegister(closeable, closeableToRef);
  		}
  	}
docs: Removes a {@link Closeable} from the registry.
  
  @param closeable instance to remove from the registry.
  @return true if the closeable was previously registered and became unregistered through this call.