受保护的意图混乱

Question

我使用这段代码打开和关闭Android 4.1.2设备的飞行模式：

boolean isEnabled = Settings.System.getInt(
                     getContentResolver(),
                     Settings.System.AIRPLANE_MODE_ON, 0) == 1;
         Settings.System.putInt(
                 getContentResolver(),
                 Settings.System.AIRPLANE_MODE_ON, isEnabled ? 0 : 1);

         Intent intent = new Intent(Intent.ACTION_AIRPLANE_MODE_CHANGED);
         intent.putExtra("state", !isEnabled);
         sendBroadcast(intent);

但在阅读完文档后我感到困惑，因为这就是它所说的：

public static final String ACTION_AIRPLANE_MODE_CHANGED
Broadcast Action: The user has switched the phone into or out of Airplane Mode. One or more radios have been turned off or on. The intent will have the following extra value:

    state - A boolean value indicating whether Airplane Mode is on. If true, then cell radio and possibly other radios such as bluetooth or WiFi may have also been turned off

**This is a protected intent that can only be sent by the system.** 

那么代码是如何工作的呢？当我说这是受保护的意图时我发送了这个意图？