I use eclipse for a API development project. As usual, I added the API libraries as jars into my (Java Build Path->Libraries).
The problem is that when I start runnung the application in debug mode, it stops on a thread which refers to the API code with 2 symptoms :
1- It says "Source not found" in the Class File Editor and expects me to "Attach Source".
2- It shows a Thread Suspended in the Debug Window with a NullPointerException
In order to get rid of the first issue, I added the API packages in the Preferences->Java->Debug->Step Filtering step. This didn't work !
In order to adress it over the exception, I disabled "Suspend execution on uncaught exceptions" parameter. This didn't work either !
Do you gave the source files for the JARs? If so, go to Java Build Path | Libraries, expand the JAR and there will be a source file attachment entry. Click on that and browse to the source file(s).