EtcdLease should not use ListenableFuture directly

[oza]

Currently, EtcdLease exposes com.google.common.util.concurrent.ListenableFuture as a part of API. If ListenableFuture is used directly, it will conflict with user-side guava library. Instead, ListenableSetFuture in #45 or some wrapper class in com.coreos.jetcd should be used to avoid the problem.

[lburgazzoli]

This is related to #16.
IMHO best would be to shade guava and use CompletableFutures as suggested by @jurmous

[oza]

@lburgazzoli thanks for the notification. I will also check #16.

I have a patch to shade Guava into jetcd locally, so I can send a PR soon. However, it can increase the size of binary. Can we accept it?

[lburgazzoli]

I do not know, but having had quite a few issues with guava dependencies I would really like not to do it again ;)

[oza]

Thanks for your comment. I agree with you. Created #47. I appreciate if you take look.

[fanminshi]

closing via #109