UweTrottmann/SeriesGuide — comment on commit ee25599df087d9a4812d5f765c589be8f247ab90
File:  line 0
By JakeWharton:

You could also have `ServiceManager` be a singleton too. It was designed to be set up once and then work as a factory for services. Every service instance is also a factory for the method instances of an underlying class so you wouldn't have to worry about any threading concerns.