关于接口参数类型问题

[huafresh]

如果接口这么定义：
int add(int a, Integer b);
会报异常：
2020-03-01 16:51:58.608 15114-15114/com.hua.myandromeda E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.hua.myandromeda, PID: 15114
java.lang.NullPointerException: Expected to unbox a 'int' primitive type but was returned null
at $Proxy0.add(Unknown Source)
at com.hua.myandromeda.MainActivity$2.onClick(MainActivity.java:31)
at android.view.View.performClick(View.java:6597)
at android.view.View.performClickInternal(View.java:6574)
at android.view.View.access$3100(View.java:778)
at android.view.View$PerformClick.run(View.java:25885)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
点击事件代码：
IApi apiService = InterStellar.with(MainActivity.this).getRemoteService(IApi.class);
int add = apiService.add(4, 5);