Select the Edit Source Lookup... command [ ] to open the Source Path Dialog, which allows you to make changes to the source lookup path of the selected debug target.
The Source Path Dialog:
Debugger
Local debugging
Remote debugging
Changing debugger launch options
Connecting to a remote VM with the Remote Java application launch configuration
Disconnecting from a VM
Launching a Java program
Preparing to debug
Resuming the execution of suspended threads
Running and debugging
Stepping through the execution of a program
Suspending threads