docs: Collection<AsteriskChannel> getChannels()
      {
          Collection<AsteriskChannel> copy;
  
          synchronized (channels)
          {
              copy = new ArrayList<>(channels.size() + 2);
              for (AsteriskChannel channel : channels.values())
              {
                  if (channel.getState() != ChannelState.HUNGUP)
                  {
                      copy.add(channel);
                  }
              }
          }
          return copy;
      }