Just an FYI for those who are developing with V2.0.2.124 For Android Studio - the HHSampleApp when you compile and then attempt to run on MC3300XR running Android 11.

You will find that the RFID Status: will not show a connection.

This is not a Bug - it was a subtle miss.

In the RFIDHandler.java file on line 269.  you will find: "readers = new Readers(context, ENUM_TRANSPORT.SERVICE_USB);" 
This is great for eConnex readers like the RFD40 / RFD90  - but is problematic for MC3300XR which would use: "readers = new Readers(context, ENUM_TRANSPORT.SERVICE_SERIAL);"

But 123RFID Mobile for Android, And the SDKSample V2.0.2.116 did this as follows:

"readers = new Readers(context, ENUM_TRANSPORT.ALL);"  

Using "ALL" will find ANY reader.