docs: void handleAgentCompleteEvent(AgentCompleteEvent event)
      {
          AsteriskAgentImpl agent = getAgentByAgentId(event.getChannel());
          if (agent == null)
          {
              logger.error("Ignored AgentCompleteEvent for unknown agent " + event.getChannel());
              return;
          }
          agent.updateState(AgentState.AGENT_IDLE);
      }