[Feature Request] Spring Feature Flags from Multiple Stores

[mrm9084]

Original from: https://github.com/Azure/AppConfiguration/issues/358

Because of the format of Feature Flag configuration, loading feature flags from multiple store results in only the last store loaded i.e. store[0], or the highest priority store with feature flags.

When loading multiple stores feature flags should be merged with last store having priority.

i.e. I have Stores A and B, where A is priority: Store A has Alpha = true Beta = false

Store B has Beta = true Gama = true

Feature Management would return Alpha = true Beta = false Gama = true