Based on laurentsd's suggestion to use code from the VmDataProviderImpl example, I refactored my plugin's service layer to use the injected UserSession OSGI service to obtain the session for the connected vCenter.
However, the method called getServiceContent that I lifted from the VmDataProviderImpl class is failing due to a "PKIX path building failed" exception. If I understood one of laurentsd's previous comments, the whole point of using the UserSession object is to leverage an already authenticated connection for obtaining the sessions for the vCenters. If this is the case, I do not understand why I'm getting the PKIX exception. I even installed the shared SSO's certificate into the vCenter's Java Keystore as I had done before for some other example but that didn't help. Is there any way to get around this exception? Any thoughts on the matter would be greatly appreciated!