[MDEP-690] go-offline fails when optional dependencies cannot be resolved

**[Stephan Schroevers](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=stephan202)** opened **[MDEP-690](https://issues.apache.org/jira/browse/MDEP-690?redirect=false)** and commented

Consider the following dummy project:

```xml

4.0.0

com.example
example
0.0.1-SNAPSHOT

io.projectreactor.addons
reactor-extra
3.3.3.RELEASE

```

Running `org.apache.maven.plugins:maven-dependency-plugin:3.1.1:go-offline` against this project passes. With version 3.1.2 the goal fails with:

```
org.eclipse.aether.resolution.DependencyResolutionException: Could not find artifact org.eclipse.swt:org.eclipse.swt.gtk.linux.x86_64:jar:4.5.2 in central (https://repo.maven.apache.org/maven2)
```

The reason for the failure appears to be that `reactor-extra` declares an
[optional](https://repo1.maven.org/maven2/io/projectreactor/addons/reactor-extra/3.3.3.RELEASE/reactor-extra-3.3.3.RELEASE.pom) dependency on `org.eclipse.swt.gtk.linux.x86_64`, an artifact which is not present in Maven Central.

It'd be nice if the version 3.1.1 behavior of the plugin could be reinstated. Alternatively (perhaps better?) it should be possible to conditionally exclude optional dependencies, just like the goal allows one to exclude dependencies by artifact ID, group ID, classifier, scope and type.

---

**Affects:** 3.1.2

2 votes, 5 watchers

Start with the org.apache.maven.plugins:maven-dependency-plugin:3.1.1:go-offline and 3.1.2:go-offline entry points, using the dummy project and reactor-extra dependency described in the issue. Compare dependency resolution for the optional SWT artifact; done means go-offline no longer fails as in 3.1.2, or supports the requested conditional exclusion behavior, with coverage for the reported case.

Written by the indexing model from the issue text.