Attaching source to an external jar in an android eclipse project [duplicate]
It seems like this was broken in Android SDK, as reported in this bug:
http://code.google.com/p/android/issues/detail?id=28658
It seems like there's a workaround as shown here:
https://android-review.googlesource.com/#/c/35702/
As the workaround was only fixed recently, it may not be available in the latest version of the SDK, the status of the issue would seem to suggest it's not available yet, though I've not tried it myself, so may be corrected.