Upgrade to Mockito 2.10.0

[wilkinsona]

There are some small breaking changes involved here

[wilkinsona]

Let's wait for the resolution of #10247 before tackling this.

[TimvdLippe]

I would like to make Spring also aware of the commitment of Mockito to support all projects by our public API. If you are relying on internal (org.mockito.internal.*) implementation, we can not guarantee no breaking changes on minor/patch updates.

Lately @szczepiq has worked on supporting PowerMockito with only a public API (check out mockito/mockito#1110) and we would like to do this for other frameworks as well. If you would like to spend some more effort and time on this issue, feel free to reach out to us to start the discussion!

And as always, thanks for using Mockito 😄

(We are especially focusing on this issue with the upcoming modularization of Java 9, which might break existing projects)

[philwebb]

Thanks @TimvdLippe. I've raised #10352 to see if we can address this. I have a feeling that it might be difficult to get there with Spring Boot 2.0, but we should certainly try.