code: public synchronized void sendContextStatus(
        final ReefServiceProtos.ContextStatusProto contextStatusProto) {
  
      // TODO[JIRA REEF-833]: Write a test that verifies correct order of heartbeats.
      final Collection<ReefServiceProtos.ContextStatusProto> contextStatusList = new ArrayList<>();
      contextStatusList.add(contextStatusProto);
      contextStatusList.addAll(this.contextManager.get().getContextStatusCollection());
  
      final EvaluatorRuntimeProtocol.EvaluatorHeartbeatProto heartbeatProto =
          this.getEvaluatorHeartbeatProto(
              this.evaluatorRuntime.get().getEvaluatorStatus(),
              contextStatusList, Optional.<ReefServiceProtos.TaskStatusProto>empty());
  
      this.sendHeartBeat(heartbeatProto);
    }
docs: Called with a specific ContextStatus that must be delivered to the driver.