code: protected FoundAgent resolve (ClientObject client, int agentId, String resolver)
      {
          com.threerings.presents.dobj.DObject dobj = _omgr.getObject(agentId);
          if (dobj == null) {
              log.warning("Non-existent agent", "function", resolver, "agentId", agentId);
              return null;
          }
  
          if (!(dobj instanceof AgentObject)) {
              log.warning("Object not an agent", "function", resolver, "obj", dobj.getClass());
              return null;
          }
  
          AgentObject agent = (AgentObject)dobj;
          Bureau bureau = _bureaus.get(agent.bureauId);
          if (bureau == null) {
              log.warning("Bureau not found for agent", "function", resolver, "agent", agent.which());
              return null;
          }
  
          if (!bureau.agentStates.containsKey(agent)) {
              log.warning("Bureau does not have agent", "function", resolver, "agent", agent.which());
              return null;
          }
  
          if (client != null && bureau.clientObj != client) {
              log.warning("Masquerading request", "function", resolver, "agent", agent.which(),
                          "client", bureau.clientObj, "client", client);
              return null;
          }
  
          return new FoundAgent(bureau, agent, bureau.agentStates.get(agent));
      }
docs: Does lots of null checks and lookups and resolves the given information into FoundAgent.