Would you clarify whether a library should or should not declare flogger-system-backend dependency?

From the [flogger documentation](https://google.github.io/flogger/):


It says:

> All code that uses flogger should depend on com.google.flogger:flogger: and com.google.flogger:flogger-system-backend:.

This is strange from my experience of slf4j and logback. If the relationship of flogger and flogger-system-backend is the same as slf4j and logback, then libraries that use flogger should not declare dependency on flogger-system-backend; otherwise the runtime that use multiple of these libraries may end up having different logging backends. http://www.slf4j.org/manual.html#libraries says:

> Embedded components such as libraries or frameworks should not declare a dependency on any SLF4J binding but only depend on slf4j-api.

Would you add a similar guidance in flogger documentation?