New Flutter master update blocs use of HiveGenerator

**Steps to Reproduce**

> Flutter 1.16.4-pre.52 • channel master • https://github.com/flutter/flutter.git
> Framework • revision 2a649b16e2 (55 minutes ago) • 2020-03-31 16:16:25 -0700
> Engine • revision 807ca8543c
> Tools • Dart 2.8.0 (build 2.8.0-dev.18.0 e8c4aed700)
>
**ERROR**

> Because no versions of hive_generator match >0.7.0+2 <0.8.0 and hive_generator 0.7.0+2 depends on dartx ^0.2.0, hive_generator ^0.7.0+2 requires dartx ^0.2.0.
> And because no versions of dartx match >0.2.0 <0.3.0, hive_generator ^0.7.0+2 requires dartx 0.2.0.
> And because dartx 0.2.0 depends on quiver >=2.0.3 <2.1.0 and every version of flutter_test from sdk depends on quiver 2.1.3, hive_generator ^0.7.0+2 is incompatible with flutter_test from sdk.
> So, because fritter_for_reddit depends on both flutter_test any from sdk and hive_generator ^0.7.0+2, version solving failed.
> pub get failed (1; So, because fritter_for_reddit depends on both flutter_test any from sdk and hive_generator ^0.7.0+2, version solving failed.)