code: public synchronized Map<String, String> getConnectionListeners()
     {
        Map<String, String> result = new TreeMap<>();
  
        for (Map.Entry<ConnectionListener, Exception> entry : listeners.entrySet())
        {
           String id = Integer.toHexString(System.identityHashCode(entry.getKey()));
           StringBuilder sb = new StringBuilder();
  
           for (StackTraceElement ste : entry.getValue().getStackTrace())
           {
              sb = sb.append(ste.getClassName());
              sb = sb.append(":");
              sb = sb.append(ste.getMethodName());
              sb = sb.append(":");
              sb = sb.append(ste.getLineNumber());
              sb = sb.append(newLine);
           }
  
           result.put(id, sb.toString());
        }
        
        return result;
     }
docs: {@inheritDoc}