add access artifact properties through api

[bvfalcon]

Closes issue #6062.

[chrisrueger]

@bvfalcon thanks for your PR. Could you please sign the commit as described here?

Depends a bit on your git client. In Github Desktop it is e.g. possible via "ammend commit" and then add your sign off to the description e.g.

But command line works as well.

[pkriens]

You need to sign the commit, see https://github.com/bndtools/bnd/pull/6080/checks?check_run_id=23608761603

[pkriens]

You ran in a baseline error:

/home/runner/work/bnd/bnd/biz.aQute.repository/src/aQute/p2/api/package-info.java:0: error: Baseline mismatch for package aQute.p2.api, MINOR change. Current is 1.4.0, repo is 1.4.0, suggest 1.5.0 or -
MINOR                PACKAGE    aQute.p2.api
  MINOR              CLASS      aQute.p2.api.Artifact
    ADDED            METHOD     getProperties()
      ADDED          RETURN     java.util.Map
    ADDED            METHOD     getProperty(java.lang.String)
      ADDED          RETURN     java.lang.String
    ADDED            METHOD     setProperties(java.util.Map)
      ADDED          RETURN     void

If you made the changes in Eclipse with bndtools you'd noticed this direct. You should also build before pushing because this error also shows up in the gradlew build.

Just bump the version in biz.aQute.repository/src/aQute/p2/api/package-info.java

[pkriens]

Next time will be a bit smoother after all the hurdles you had to jump so far :-)