Why do I receive a 'No Qualifying Bean Found" error when installing a plugin that uses both SAL and JIRA UserManager classes?

I don’t know why either by if you override the bean name with the annotation, you can resolve that problem. I was using SAL UserManager elsewhere in the Plugin and was running into the usual errors when trying to use Jira Util UserManager.

public class Service {
    private final GroupManager groupManager;
    private final UserManager userManager;