Exported service does not require permission: what does it mean?

I had the same issue when I updated SDK to version 20. I removed it adding android:exported property android:exported="false" like so:

<service android:name=".MyService"
    android:exported="false">
    <intent-filter>
        <action android:name="org.example.android.myservicedemo.IService" />
    </intent-filter>
</service>

See this doc