It's not in jbossesb-rosetta which I already depend on. I've looked at http://mavenhub.com/c/org/jboss/soa/esb but I can't seem to find it. I suppose I can always include it as a system dependency but only as a last resort.
1) That artifact is not present in Maven Central, explaining why Maven cannot find it by default:
http://search.maven.org/#search|ga|1|a%3A%22jbossesb-soap%22
2) Jboss artifacts are hosted by a separate Nexus repository. A search there was similarily fruitless:
https://repository.jboss.org/nexus/index.html#nexus-search;gav~~jbossesb-soap~~~
3) A Google search threw up this same unanswered question on Jboss community forum:
https://community.jboss.org/thread/154253
Seems you are left with only one option. Upload the required jar into your own Maven respository so that the dependency can be found.
If you want to simply hack the jar into your current build, then I would recommend installing it into your local repository. Do not use system scope dependencies.
Jars can be installed locally using the Maven install plugin