fix: adopt properties of underlying Geant4GeneratorAction in Geant4SharedGeneratorAction

[wdconinc]

This PR addresses the issue outlined in #1240 (comment)

making the GeneratorAction shared with DDG4.GeneratorAction(kernel, "Geant4InputAction/hepmc%d" % index, shared=True) fails because the properties (Parameters, Input) that are subsequently set are [...] not exposed to the GeneratorAction handle gen.

This PR brings the handling of the Geant4SharedGeneratorAction in line with other shared actions. With this PR, the following diff functions without runtime exceptions now.

diff --git a/DDG4/python/DDSim/DD4hepSimulation.py b/DDG4/python/DDSim/DD4hepSimulation.py
index 11ed0e83..9fe46eda 100644
--- a/DDG4/python/DDSim/DD4hepSimulation.py
+++ b/DDG4/python/DDSim/DD4hepSimulation.py
@@ -390,11 +390,11 @@ class DD4hepSimulation(object):
         gen.Input = "Geant4EventReaderHepEvtLong|" + inputFile
       elif inputFile.endswith(tuple([".hepmc"] + HEPMC3_SUPPORTED_EXTENSIONS)):
         if self.hepmc3.useHepMC3:
-          gen = DDG4.GeneratorAction(kernel, "Geant4InputAction/hepmc%d" % index)
+          gen = DDG4.GeneratorAction(kernel, "Geant4InputAction/hepmc%d" % index, shared=True)
           gen.Parameters = self.hepmc3.getParameters()
           gen.Input = "HEPMC3FileReader|" + inputFile
         else:
-          gen = DDG4.GeneratorAction(kernel, "Geant4InputAction/hepmc%d" % index)
+          gen = DDG4.GeneratorAction(kernel, "Geant4InputAction/hepmc%d" % index, shared=True)
           gen.Input = "Geant4EventReaderHepMC|" + inputFile

BEGINRELEASENOTES

• adopt properties of underlying Geant4GeneratorAction in Geant4SharedGeneratorAction

ENDRELEASENOTES

[github-actions]

Test Results

   16 files     16 suites   6h 49m 38s ⏱️
  371 tests   371 ✅ 0 💤 0 ❌
2 895 runs  2 895 ✅ 0 💤 0 ❌

Results for commit 7cd62d0.

[MarkusFrankATcernch]

Thanks for spotting.
For the generator action this was mysteriously forgotten. All other shared actions share the properties.