code: public synchronized void close()
                      throws ObjectManagerException
      {
          // Invalidate out all ManagedObjects in inMemory Tokens to prevent them
          // from being used after shutdown.
          for (java.util.Iterator tokenIterator = inMemoryTokens.values().iterator(); tokenIterator.hasNext();) {
              java.lang.ref.Reference reference = (java.lang.ref.Reference) tokenIterator.next();
              if (reference != null) {
                  Token token = (Token) reference.get();
                  if (token != null)
                      token.invalidate();
              } // if (reference != null).
          } // for inMemoryTokens.
  
          // Help garbage collection. 
          inMemoryTokens.clear();
          inMemoryTokens = null;
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.ws.objectManager.ObjectStore#close()