Currently, our "Android" flavor of Guava supports 2 use cases:
- Android users (API level 15 (Ice Cream Sandwich) and up)
- Java 7 users
We are definitely not going to start using Java 8 APIs. Thus, we are not going to increase our minimum Android version to 24, nor are we going to require our users to enable library desugaring. In short: We'll continue to support older versions of Android with no changes on users' part.
However, we are investigating whether to stop supporting non-Android users who use Java 7. This would let us simplify some implementations (mainly by using lambdas), but more importantly, it would let us make some API improvements -- like
default methods on interfaces and type annotations (such as for nullness).
This is part of a larger effort by many Google projects to consider dropping support for Java 7. Please let us know if you anticipate problems from this change -- mainly, if you are using Guava in your library or app and you support Java 7. Thanks.
(Please also spread the word. I have additionally filed an issue about this. Later, we may also try to introduce some warnings when Guava is run under Java 7.)