Fixed concurrency bug that could be triggered via the React Native plugin

[kstenerud]

Goal

DeviceDataCollector.generateDevice makes a clone of its internal runtimeVersions map, which can also be modified by calling addRuntimeVersionInfo. This can cause a concurrency exception in some cases.

Design

Switched to a copy-on-write approach to sidestep the issue.

Testing

New unit test to verify that the new code is concurrency-safe.

[bugsnagbot]

Android notifier sizes

Format	Size impact of Bugsnag (kB)	Size impact of Bugsnag when Minified (kB)
APK	0.0	0.0
arm64_v8a	0.0	0.0
armeabi_v7a	0.0	0.0
x86	0.0	0.0
x86_64	0.0	0.0

Generated by 🚫 Danger

[lemnik]

I'm not convinced that we should be opening up our classes just to satisfy Mockito limitations.

We should rather look at:

• The kotlin-allopen gradle plugin
• Upgrading Mockito to a version that supports mocking final Android classes (this will have a knock-on effect to our min Android version support)
• Avoiding the need for mocks in this test (I doubt this is realistic)

For now I'd also be willing to drop the unit test if it proves too invasive.

[kstenerud]

Alright, I'm leaving the test code there (commented out) because it's a pain to write. Once we can figure out a better solution we can enable it again.

[lemnik]

LGTM