Proposal: VisibleForAccessors

[ZacSweers]

On android we have method limits, and one means of mitigating them is to avoid synthetic accessor methods. A downside of this would be that sometimes you're left making certain things package-local when you'd normally make them private. What would you think of an annotation like @VisibleForAccessors(otherwise = PRIVATE)? Similar to @VisibleForTesting, but to enforce these are treated the same way as otherwise (whose value could default to PRIVATE) during compilation,

[ZacSweers]

An example: uber/AutoDispose#103

[NightlyNexus]

There is an Android Lint rule for @RestrictTo, as you know, but this proposal may be handy for non-Android libraries.

My personal experience is that Java's private keyword is useless noise in libraries and all feature-package organized code.
@VisibleForAccessors(otherwise = PRIVATE) would also be a lot of noise for little clarity or other benefit, in my opinion.

However, an annotation like this would be handy to apply to packages in Java libraries that organize some implementation details in separate packages like internal, so they could restrict consumers from using code not intended to be part of the API.

[JakeWharton]

Dupe of #537

[JakeWharton]

Or related to, at least

[bangarharshit]

Error-Prone already has a check for RestrictTo RestrictToEnforcer.

There is also a RestricedApiChecker which enforces whitelisting on some path.

It can be very verbose and is only true for methods.

A similar test can be added to this suit. I can send a PR if the error-prone team is ok about the check.

This issue can then be closed in favor of #537.