laurentsd, thank you for the quick response.
Based on your quote:
It is not possible for the same code containing this error to work in your dev environment so there must be a difference between the two.
... I tested my SDK system, and it still works. I then went to my test/prod/non-sdk vCenter, restarted the web client service, and once it was ready, it still fails in the same way. I did a 4-way-diff on the bundle-context.xml and bundle-context-osgi.xml files and found that they are all identical (details provided below). Since you indicate that what I'm seeing shouldn't be possible and yet I am seeing it happen, it would seem to me that I must have a setup issue. I tried to follow all of the documentation, but perhaps I mis-read something. I don't know if anyone else has seen what I am seeing.
My vCenter system is the system I had previously been running my C# (old) vSphere Client plugins on, so it has been in place for a while... perhaps when I set up my SDK system, something is out of sync. I will continue to look and post back if/when I find something.
--- BundleContext Details ---
On my SDK system, I took the files from my project area and from the "stage" area of the web client. I also took them from the ZIP file that I had placed on my publicly available web-server which my registration file points to. On my test/prod/non-sdk system, I took them from the vc-packages directory. Specifically all of the directories are listed in the paths below (and all contain both the bundle-context.xml AND bundle-context-osgi.xml, which I will now refer to as bundle-context[-osgi].xml):
[[ My SDK System ]]
c:\STSProjects\HelloWorldJava\src\main\resources\META-INF\spring\bundle-context[-osgi].html
-- and --
c:\VMware\vsphere-web-client\server\stage\HelloWorldJava.jar
==> \META-INF\spring\bundle-context[-osgi].html
[[ My ZIP file ]]
https://my_server/my_path/HelloWorld.zip
==> \plugins\HelloWorldJava-1.0.0.jar
======> \META-INF\spring\bundle-context[-osgi].html
[[ My test/prod/non-sdk vCenter after registering my plugin ]]
c:\ProgramData\VMware\vSphere Web Client\vc-packages\vsphere-client-serenity\com.acme.helloWorldPlugin-1.0.0\plugins\HelloWorldJava-1.0.0.jar
==> \META-INF\spring\bundle-context[-osgi].html