Migrate off of jsr305

[zyxist]

There are several issues with using jsr305.jar by Guava.

JSR-305 is dormant, has been for a long while and shows no hope of ever producing an agreed set of annotations in our lifetime. Further more these annotations use javax. packages which it is not possible to use according to the Oracle Java binary licence, so applications can not use and ship these dependencies along with a JRE without violating the Oracle licence agreement.

F. JAVA TECHNOLOGY RESTRICTIONS. You may not create, modify, or change the behavior of, or authorize your licensees to create, modify, or change the behavior of, classes, interfaces, or subpackages that are in any way identified as "java", "javax", "sun", “oracle” or similar convention as specified by Oracle in any naming convention designation.

The JSR-305 group has not defined any official releases according to its jsr page so the only implementations is a seemingly random implementation provided by the FindBugs team. Even if the team where experts on the JSR (which some where) they are not official as there has been no vote and are not available from the JSR hompage - so the javax package name restriction still applies.

Using jsr305 causes additional issues, if Guava is used in a modular JDK9 applications, because it puts the annotations into javax.annotation package, which is also used by a couple of other JAR-s and a legacy JDK module java.xml.ws.annotation. If one wants to create a modular JDK9 application with two dependencies to conflicting JAR-s, Java refuses to compile and run it because of a package split. Example:

• Guava -> forces us to require jsr305 automatic module,
• Dagger -> forces us to require either java.xml.ws.annotation or jsr250 automatic module.

All of the modules use javax.annotation.

Findbugs has been rebooted as Spotbugs and they are going to make a switch from JSR-305 to their own internal annotations in version 4.0.0 that do not break anything:

spotbugs/spotbugs#180

I think Guava should consider switching to them in order not to pollute application dependencies with jsr305 JAR.

[ronshapiro]

AFAICT these are the annotations from that package that we use:

• @Nullable
• @CheckForNull
• @CheckReturnValue
• @ParametersAreNonnullByDefault
• @concurrent.GuardedBy
• @concurrent.Immutable
• @concurrent.NotThreadSafe
• @concurrent.ThreadSafe

@Nullable is probably the one that we have the most options, since almost everyone treats any annotation with the simple name of Nullable as the same.

The others are less clear to me - they're technically just for static analysis, but they all have RUNTIME retention. It's not abundantly clear how we could get around using them without having ErrorProne, IDEs, and all other static analysis pipelines adopting a new set of APIs.

It sounds like we should maybe be avoiding javax.annotation.Generated entirely until we can figure this out. This will be a large project (and span beyond just Google products). Would that solve the module issue?

[zyxist]

I agree that this is more a long-term action. I created this issue more to raise the awareness of the problems with jsr305 and new Java. Spotbugs 4.0 is not released yet, and other tools would have to agree for a new set of annotations, and provide the sufficient support. But on the other hand, Guava is in the right position to influence a decision, which way to go.

Regarding javax.annotation.Generated:

• avoiding it will only reduce the problem, not remove it (JSR-250 contains other annotations, too - if any of them is in use by any dependency or main project, you need to patch the modules).
• Java 9 provides a new, unambiguous variant: javax.annotation.processing.Generated,
• you can detect which one of them is available by the classloader, and generate the code either without any annotation, with javax.annotation.Generated, or with javax.annotation.processing.Generated. For JDK8, it would work "as usual", and for JDK9, it would depend on the required JDK module in the application module descriptor, so that the developer has a choice, which way to go.

I appreciate that you didn't forget about Generated :).

[ronshapiro]

JSR-250 contains other annotations, too

Seems to me that the others are significantly less heavily used.

[cpovirk]

Migrating off the jsr305 annotations makes sense to me.

Hopefully most tools care only about the simple class name of the annotations, not their packages. For starters, I checked Error Prone's @CheckReturnValue and @GuardedBy checkers. They care only about the simple name. But I'm sure that some tools (inside and outside Google) will care about the package.

If we're moving off the "standard" annotations, I wonder what it makes the most sense for us to migrate to. Spotbugs is a natural choice, since we know it has all the annotations that we want. But of course there are many nullability annotations. And arguably we aren't targeting Spotbugs nowadays so much as we're targeting Error Prone. Maybe Error Prone would be interested in adding some annotations of their own. Or maybe, for some of the annotations we use less frequently, we could have our own (package-private?) versions to avoid committing to any tool.

(One other note about @Nullable: We can't use type annotations yet because we currently make our "Android" branch available to Java 7 users. This may rule out some libraries' nullness annotations.)

[jbduncan]

If we're moving off the "standard" annotations, I wonder what it makes the most sense for us to migrate to.

Adopting the Checker Framework's annotations may make sense here. Considering that, AFAIK, its nullability annotations are the most plentiful and advanced out there, it may encourage more people to try the framework out.

But if its annotations count as type annotations, then we'd be unable to use them...

[JakeWharton]

Hopefully most tools care only about the simple class name of the annotations, not their packages.

This is not true of Kotlin, although they'll be receptive to adding your annotations to their list.

[kashike]

Looking at the options, it seems to me that Checker Framework would be a good solution. Thanks for pointing me to that, @jbduncan.

[kashike]

I'm curious what the replacement for javax.annotation.concurrent.Immutable is with Checker Framework, if there is one - do you happen to know, @jbduncan?

[jbduncan]

@kashike I admit that I don't know if the Checker Framework has an Immutable annotation, but I do know that error-prone's annotations project has one. I've never tried the Checker Framework personally, so I don't know how it behaves in combination with error-prone (which, by comparison, I have used), but theoretically if one can get them to work nicely together, then we'd have a superior, statically analysed solution to javax.annotation.concurrent.Immutable.

[jbduncan]

...but that's not even considering the other sorts of annotations that we're already using and will probably still want to use, like @Nullable...

This may get tricky.

[jbduncan]

The Checker Framework authors themselves suggest that their own type annotations are backwards-compatible with Java 6, but only if they're written inside comments.

That's not exactly ideal...

[kashike]

... Spotbugs is a natural choice, since we know it has all the annotations that we want. ...

Does it? I don't see everything that was listed above - it appears as if some annotations that are used by Guava are not in spotbugs.

As for Checker Framework: it appears to have most things, except @Immutable: https://gist.github.com/kashike/d8fb2007ab01041a08a2d5cf20bc2d17

...create a custom @Immutable annotation? It seems as if errorprone has one already, actually.

[jbduncan]

@kashike Apologies if I've not explained myself very well before, but I just want to make sure we're both on the same page with regards to the Checker Framework's annotations.

It seems to me from what @cpovirk's said already and what I personally know of the Checker Framework's annotations that, sadly, since they are type annotations, they can only be used in Java 8+ projects - JSR308, which is what type annotations are derived from, is only implemented in compilers that understand Java 8.

This is a problem because guava-android is compiled with a Android toolchain, and modern Android toolchains only understand Java 7 syntax and a small subset of Java 8 syntax - not enough to understand type annotations as legal constructs.

The only workaround I've found so far (suggested by the Checker Framework authors here) is to write type annotations in comments. So, for example, instead of:

List<@Nullable String> listOfNullsAndStrings = ...;

we'd have:

List</*@Nullable*/ String> listOfNullsAndStrings = ...;

The Checker Framework understands type annotations written like this, but I somewhat doubt other tools like IntelliJ IDEA, {Find,Spot}Bugs, and Google's internal tools understand them written like this too. Thus, we may not be able to use the Checker Framework's annotations in Guava until Android catches up.

If you did understand this already, apologies! Otherwise, I hope that this has cleared things up a bit. :)

[kashike]

Thanks for the reply, @jbduncan. I'm also looking at what to use in my own projects (which are Java 8) - sorry for not stating this.

I've been using com.google.code.findbugs:jsr305 for a long time now, but this issue has made me want to switch to something new (which, in this case, is currently going towards org.checkerframework:checker-qual) for annotations on things (I annotate pretty much everything that can be annotated with @Nonnull or @Nullable, as well as @Immutable). checker-qual seems to have everything except @Immutable.

I'm trying to find a replacement that has everything I need, but I haven't been able to yet. Perhaps I'll delay switching until the Guava team comes to a solution for this issue in Guava.

[cpovirk]

Progress update + summary for people new to this:

• jsr305 doesn't play well with Java 9 modules because it lives in javax.annotation, which is used by other modules.
• To address this, we're migrating Guava off the jsr305 annotations and onto those from Error Prone and the Checker Framework. This is done and will be in 23.6, except...
• We still need to make sure that Kotlin understands the new annotations, including the Checker Framework @NullableDecl and some annotation to mark parameters as non-null by default.
• Other tools that read our annotations may need to be updated to look for the new annotations. We'll mention this in our release notes.

[cgruber]

Will there be a version of guava that uses both old and new in the interim, or will this be a hard cut off between versions?

…

On Mon, Dec 11, 2017, 5:16 AM Chris Povirk ***@***.***> wrote: Progress update + summary for people new to this: - jsr305 doesn't play well with Java 9 modules <https://blog.codefx.org/java/jsr-305-java-9/> because it lives in javax.annotation, which is used by other modules. - To address this, we're migrating Guava off the jsr305 annotations and onto those from Error Prone <http://errorprone.info/> and the Checker Framework <https://checkerframework.org/>. This is done and will be in 23.6, except... - We still need to make sure that Kotlin understands the new annotations, including the Checker Framework @NullableDecl <JetBrains/kotlin#1421> and some annotation to mark parameters as non-null by default <https://youtrack.jetbrains.com/issue/KT-21408>. - Other tools that read our annotations may need to be updated to look for the new annotations. We'll mention this in our release notes. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2960 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAUN4khif1bh5T6FtA7pnt9PQdEyyEdYks5s_SsAgaJpZM4PxSdM> .

[cpovirk]

Hmm, good question. I have been hoping to just cut from one to the other, on the theory that tools can be updated to recognize both ahead of time. But if anyone knows of problems that we could avoid by having both present, let me know.

[ben-manes]

The poms for jsr305 and guava don't show a log4j dependency (at any scope). It sounds like a false positive.

[kevinb9n]

Since making this happen is in some ways more important to JSpecify right now than it even is to Guava, we're also tracking this in jspecify/jspecify#239, and that might be a better place to follow along.