Additional fix for pauldemarco/flutter_blue PR #940

[espresso3389]

pauldemarco/flutter_blue PR #940 was initially created by me and the PR was merged into boskokg/flutter_blue prematurely. This PR applies the latest changes on the branch to boskokg/flutter_blue.

[espresso3389]

Updates on example/lib/main.dart contains additional null handling codes but the style changes are not intentional...

[boskokg]

Hello @espresso3389

We published flutter_blue_plus plugin and we no longer maintain this fork.

Can you please make a new PR at flutter_blue_plus? Please make the changes more clear by creating multiple merge requests for different improvements/fixes you proposed.

1. I am not sure why you removed the method getBondedDevices
2. I see that you added targetSdkVersion to the plugin (I think that we should not do that in plugins and that others are not doing that)
3. I am not sure why we need to update rxdart: ^0.27.0 to ^0.27.3?
4. ensurePermissionBeforeAction method had a logic to accept only one type of permissions since there was a warning about using permission in the android level that doesn't support it. This was the reason why we check the android version and having only one parameter for permission(s) and doing the check inside ensurePermissionBeforeAction method, but before calling it.

[ekuleshov]

@espresso3389 do you think you could make a PR on the new flutter_blue_plus plugin?

They already pushed a few released to pub.dev and it would be great to get your fixes in there https://github.com/boskokg/flutter_blue_plus