I recently moved some code to a library project. Since then, when a crash happens in that library, the stack trace of the crash report doesn't show the line number in the library's code - Unknown Source is shown instead.
The problem is quite obvious - hard to fix an NPE if I don't know in where it happened.
Example:
java.lang.NullPointerException
at library.SomeClass2.b(Unknown Source)
at library.SomeClass1.a(Unknown Source)
at android.app.SomeClass.a(SomeClass.java:239)
...
* Note that the library project is a regular Java project - referenced from the Android project (No hanky-panky - simple eclipse java project dependency).