Documentation need to be updated on how to compile Exoplayer 2.12.0 apps with androidx.work library dependency

[Rexee]

[REQUIRED] Issue description

If you use androidx.work and ExoPlayer with version 2.12.0 you need to add additional undocumented settings to gradle file described in issue: #7905 (comment)
If Exoplayer 2.12.0 cannot work with androidx.work library without these changes, then it should be officially documented because androidx.work is really popular. Currently we need to check closed issues to find solution.
Google have similar problem and recommend to include "councurrent-futures" dependency in gradle file: https://developer.android.com/topic/libraries/architecture/workmanager/advanced/listenableworker, can this problem be solved with similar approach?

[REQUIRED] Reproduction steps

Described in #7905

[REQUIRED] Link to test content

Described in #7905

[REQUIRED] A full bug report captured from the device

Described in #7905

[REQUIRED] Version of ExoPlayer being used

2.12.0

[REQUIRED] Device(s) and version(s) of Android being used

any

[rial1106]

I had to add a the guava dependancy since listenablefuture wasn't found. It took a lot of work to find the soloution

implementation 'com.google.guava:guava:29.0-android'

[icbaker]

Thanks for flagging - I agree these errors are pretty confusing.

I've sent a change switching ExoPlayer to depend on Guava as 'api', which I believe resolves both #7905 and #7993.

I'm not going to make any additional documentation changes - in the short term people can find these issues until the 'api' dependency change is included in a release.