Warnings of depreciated API and unsafe/unchecked operations on android build

[Jonny1987]

I get the following warnings when building:

Note: /home/john/.pub-cache/hosted/pub.dev/flutter_radar-3.9.0/android/src/main/java/io/radar/flutter/RadarFlutterPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: /home/john/.pub-cache/hosted/pub.dev/flutter_radar-3.9.0/android/src/main/java/io/radar/flutter/RadarFlutterPlugin.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.