docs: public static void setConnectionHandle(VirtualConnection vc, ConnectionHandle handle) {
          if (vc == null || handle == null) {
              return;
          }
          Map<Object, Object> map = vc.getStateMap();
  
          // set connection handle into VC
          Object vcLock = vc.getLockObject();
          synchronized (vcLock) {
              Object tmpHandle = map.get(CONNECTION_HANDLE_VC_KEY);
  
              // If this connection already has a unique handle when we get here,
              // something went wrong.
              if (tmpHandle != null) {
                  throw new IllegalStateException("Connection " + tmpHandle + " has already been created");
              }
  
              map.put(CONNECTION_HANDLE_VC_KEY, handle);
          }
      }