gwt-elemental-2.8.2.vaadin1 gives duplicate dependencies

[pekam]

Our custom build gwt-elemental-2.8.2.vaadin1 is based on this:
https://github.com/denis-anisimov/gwt-elemental

It copies files from the gwt-elemental dependency into the package itself, but the original dependency is not excluded. This brings duplicate gwt-elemental dependencies for those who depend on this package (flow-server).

Original issue: #4569 had a quick fix by excluding the transitive dependency: #4594

Steps to resolve the ticket:

1. Fix the pom.xml so that the package doesn't pull the original gwt-elemental as a transitive dependency
2. Release gwt-elemental-2.8.2.vaadin2
3. Update the dependency in flow-server and remove the exclusion, which should be redundant at that point

[denis-anisimov]

I guess it's enough to use <optional>true</optional> for the original gwt-elemental dependency inside the pom.xml?

What do you think @Legioth , @tsuoanttila ?

The original dependency is needed since it's used to repackage the sources so we need it somehow present as a dependency in the pom.xml. We just don't want it to be transitive.

[Legioth]

Doesn't maven-dependency-plugin also support extracting files from artefacts that are not in the <dependencies> section? Might have to explicitly define a <version> in the plugin config then instead of as a dependency.

Otherwise, optional (or provided?) might also work, even though it's not semantically correct.

[denis-anisimov]

Yeah, OK.
I will check how maven-dependency-plugin works. If it supports then it's better to remove the dependency completely.
Otherwise let's go with optional.

Thanks.

[denis-anisimov]

Just for the reference:
it's possible to use maven-dependency-plugin without dependency section BUT
then the resulting classes can't be compiled because the original gwt-elemental has transitive dependencies which are absent after extraction.

So actually the dependency is needed for the compilation but is not needed at runtime.
So actually optional is OK in this case.