code: void removeChannel(StoredClientChannel channel) {
          lock.lock();
          try {
              mapChannels.remove(channel.id, channel);
          } finally {
              lock.unlock();
          }
          updatedChannel(channel);
      }
docs: <p>Removes the channel with the given id from this set of stored states and notifies the wallet of an update to
  this wallet extension.</p>
  
  <p>Note that the channel will still have its contract and refund transactions broadcast via the connected
  {@link TransactionBroadcaster} as long as this {@link StoredPaymentChannelClientStates} continues to
  exist in memory.</p>