Program: 94811
Project: 94811
Buggy source:
static void startMission(final DroneManager droneMgr,final boolean forceModeChange,final boolean forceArm,final ICommandListener listener){
  if (droneMgr == null) {
    return;
  }
  final Drone drone=droneMgr.getDrone();
  final Runnable sendCommandRunnable=new Runnable(){
    @Override public void run(){
      msg_command_long msg=new msg_command_long();
      msg.target_system=drone.getSysid();
      msg.target_component=drone.getCompid();
      msg.command=MAV_CMD.MAV_CMD_MISSION_START;
      drone.getMavClient().sendMavMessage(msg,listener);
    }
  }
;
  final Runnable modeCheckRunnable=new Runnable(){
    @Override public void run(){
      if (drone.getState().getMode() != ApmModes.ROTOR_AUTO) {
        if (forceModeChange) {
          changeVehicleMode(drone,VehicleMode.COPTER_AUTO,new AbstractCommandListener(){
            @Override public void onSuccess(){
              sendCommandRunnable.run();
            }
            @Override public void onError(            int executionError){
              postErrorEvent(executionError,listener);
            }
            @Override public void onTimeout(){
              postTimeoutEvent(listener);
            }
          }
);
        }
 else {
          postErrorEvent(CommandExecutionError.COMMAND_DENIED,listener);
        }
        return;
      }
 else {
        sendCommandRunnable.run();
      }
    }
  }
;
  if (!drone.getState().isArmed()) {
    if (forceArm) {
      arm(drone,true,new AbstractCommandListener(){
        @Override public void onSuccess(){
          modeCheckRunnable.run();
        }
        @Override public void onError(        int executionError){
          postErrorEvent(executionError,listener);
        }
        @Override public void onTimeout(){
          postTimeoutEvent(listener);
        }
      }
);
    }
 else {
      postErrorEvent(CommandExecutionError.COMMAND_FAILED,listener);
    }
    return;
  }
  modeCheckRunnable.run();
}

Fixed version (ground truth):
static void startMission(final DroneManager droneMgr,final boolean forceModeChange,final boolean forceArm,final ICommandListener listener){
  if (droneMgr == null) {
    return;
  }
  final Drone drone=droneMgr.getDrone();
  final Runnable sendCommandRunnable=new Runnable(){
    @Override public void run(){
      msg_command_long msg=new msg_command_long();
      msg.target_system=drone.getSysid();
      msg.target_component=drone.getCompid();
      msg.command=MAV_CMD.MAV_CMD_MISSION_START;
      drone.getMavClient().sendMavMessage(msg,listener);
    }
  }
;
  final Runnable modeCheckRunnable=new Runnable(){
    @Override public void run(){
      if (drone.getState().getMode() != ApmModes.ROTOR_AUTO) {
        if (forceModeChange) {
          changeVehicleMode(drone,VehicleMode.COPTER_AUTO,new AbstractCommandListener(){
            @Override public void onSuccess(){
              sendCommandRunnable.run();
            }
            @Override public void onError(            int executionError){
              postErrorEvent(executionError,listener);
            }
            @Override public void onTimeout(){
              postTimeoutEvent(listener);
            }
          }
);
        }
 else {
          postErrorEvent(CommandExecutionError.COMMAND_FAILED,listener);
        }
        return;
      }
 else {
        sendCommandRunnable.run();
      }
    }
  }
;
  if (!drone.getState().isArmed()) {
    if (forceArm) {
      arm(drone,true,new AbstractCommandListener(){
        @Override public void onSuccess(){
          modeCheckRunnable.run();
        }
        @Override public void onError(        int executionError){
          postErrorEvent(executionError,listener);
        }
        @Override public void onTimeout(){
          postTimeoutEvent(listener);
        }
      }
);
    }
 else {
      postErrorEvent(CommandExecutionError.COMMAND_FAILED,listener);
    }
    return;
  }
  modeCheckRunnable.run();
}