gwt-dev contains common java classes (like org.w3c.dom), causing conflicts

[butlnor]

I don't know the reasons why "gwt-dev.jar" contains a lot of "garbage", like the whole "org.w3c.dom", which causes conflict with Java 9+, since DOM is already present in JRE, and Java 9+ module system doesn't allow same packages in different JAR files.

Please make sure that gwt-dev.jar is build without such common libraries! It is completely wrong to pack stuff, that is already present elsewhere. Currently, I will have to strip those classes out of JAR file, but this means I will have a modified custom JAR file, so it will not work with other team members (unless we all use the same modified JAR).

[tbroyer]

Get the JARs from the Central Repository, they don't contain those classes. The JARs from the ZIP distribution are designed to be "easy to use" from simple scripts (including Ant without Ivy), so you don't have to list too many files in your classpath (also, I don't think GWT works with the module path / JPMS, but AFAIK even those fat jars work with Java 9+ as long as you only use the classpath).

[butlnor]

Hm, in Maven central repo, there is really a smaller file. But this is chaotic, having two different JAR files. Shoudn't it then be better to name the first one as "gwt-dev-full.jar"?

I understand, that sometimes it's better to include some 3rd party stuff, to simplify the building, but NOT including the common stuff like org.w3c.dom, which is already included in every JRE! It's ok to include things like Apache commons or similar, but not JRE things.

[butlnor]

Well, the one in central repo has too few classes... missing almost every 3rd party lib, so I have to add them manually.
I think the solution now it to use the JAR from ZIP, but remove all those wrong classes from it, that should never be there.

[niloc132]

We can look into removing this, as GWT only supports Java 11+ at this time.

That said, you can you describe the problem that this is causing, how you're able to use the gwt-dev.jar with JPMS? I would be very surprised to find that gwt-dev.jar's classes work when loaded from JMPS, with or without these types present. Especially for these types, gwt-dev.jar would need java.xml explicitly as a module dependency to use as you describe?

If there's a concrete benefit it probably makes sense to overhaul with #10011, as that will need lots of testing to be sure that shaded/uber jars behave as expected in all supported use cases. Including other dependencies also causes problems, so I don't like how comfortable GWT has historically been with this either.

[butlnor]

It was enough to strip out "org.w3c.dom". This seems to be the only problematic inclusion. Since JRE already contains those classes.

So, if you just omit org.w3c.dom, I think this will suffice.

[niloc132]

So that we can add some semblance of testing to this use case, can you describe or demonstrate how you're running, and give details for the problem that is happening? If this is a requirement of the tool, we need to be able to verify that the fix works.

Also, can you be specific about how you've used this in the past - is this a new project, or are you just now updating from Java 8 so that this is becoming a new problem?