LeakCanary检测不出静态变量的泄露

public class MainActivity extends AppCompatActivity {

    private static Activity mActivity;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mActivity = this;
    }
}

为什么LeakCanary检测不出这个泄露呢？等了半天都没反应