Each unique instance of this class represent a State of the TemplateClassLoader.
When some classCache is reloaded, them the TemplateClassLoader get a new state.
This makes it easy for other parts of Play to cache stuff based on the
the current State of the TemplateClassLoader..
They can store the reference to the current state, then later, before reading from cache,
they could check if the state of the TemplateClassLoader has changed..