Supply a Preconditions in common location

[pisv]

This is a follow-up to #798, which handles Preconditions similarly to ToStringBuilder.

See #742 for detailed discussion.

[pisv]

Note that #798 needs to be merged first.

[jonahgraham]

I had another PR almost ready to go on this topic, but I didn't get it up before the end of the day.

I was a little more weary of removing Preconditions because it is referenced from a number of places: https://github.com/search?q=Preconditions.enableNullChecks&type=code

Do you think it is ok to have the breaking change that says means consumers need to change their imports? I assume that no one is really depending on the sort of scoping that the enableNullChecks provides by having multiple copies.

[jonahgraham]

The documentation added in #799 needs to be updated too.

[jonahgraham]

My alternate is in #801

[jonahgraham]

After more thought I want to go with this version and since there are already breaking changes in 0.22.0 compared to 0.21.0 I think we should remove rather than just deprecate the old Preconditions.

@pisv before I rebase and merge this I will wait a little while for your comment. I am trying to complete the 0.22.0 today if possible.

[pisv]

After more thought I want to go with this version and since there are already breaking changes in 0.22.0 compared to 0.21.0 I think we should remove rather than just deprecate the old Preconditions.

Makes sense to me, although both alternatives have their merits...

[jonahgraham]

I have rebased and pushed. On successful build I will merge this.

[pisv]

The documentation added in #799 needs to be updated too.

Looks like I have completely missed that part, sorry... Unfortunately, I'll not be able to do it right now.

[jonahgraham]

No worries. I forgot to do it too. I miss Gerrit, it warns me before merging if there are unresolved comments.

I have the update on my other pr and will provide it soon.

[jonahgraham]

I have the update on my other pr and will provide it soon.

Done in #804