docs: public boolean unregisterChaincodeEventListener(String handle) throws InvalidArgumentException {
          boolean ret;
  
          if (shutdown) {
              throw new InvalidArgumentException(format("Channel %s has been shutdown.", name));
          }
  
          checkHandle(CHAINCODE_EVENTS_TAG, handle);
  
          synchronized (chainCodeListeners) {
              ret = null != chainCodeListeners.remove(handle);
  
          }
  
          synchronized (this) {
              if (null != blh && chainCodeListeners.isEmpty()) {
  
                  unregisterBlockListener(blh);
                  blh = null;
              }
          }
  
          return ret;
  
      }