This is a regression introduced in flutter/plugins#2488
The getActivityHashCode is unnecessary, we should revert back to how it was before flutter/plugins#2488: caching the hashCode when initialize the map and always use the cached value.

Also, V2 embedding does not use the activityHashCode, which makes another point that we can remove getActivityHashCode and use a cached value for V1 embedding.

Also see https://github.com/flutter/plugins/pull/3206/files#r512392320 for more details