[ARCHETYPE-535] DefaultPomManager.mergePoms ignores properties if the model has no dependencies

**[ajbanck](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=ajbanck)** opened **[ARCHETYPE-535](https://issues.apache.org/jira/browse/ARCHETYPE-535?redirect=false)** and commented

In DefaultPomManager.java mergeModelBase the line
model.getProperties().putAll( generatedModel.getProperties() );
is nested inside ( String generatedDependencyId : generatedDependenciesByIds.keySet() )
so if the set of generated dependencies is empty the properties are not copied.

Esp. for profiles it's more common to have no dependencies resulting in missing properties

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