Steps to reproduce:

- Create a UML 'Java-Platform Model' project, 
  uncheck 'Source-Model Synchronization' check box
- Create a Class diagram
- Put Package element on the diagram and name it 'pack1'
- Put Class element on 'pack1' Package element and name it 'MyClass'

- Put Package element on the diagram and name it 'pack2'
- Put Interface element on 'pack2' Package element and name it 'MyInterface'
- Insert 'public void run()' operation into 
  'MyInterface' Interface element

- Draw 'Implementation' link from 'MyClass' to 'MyInterface'
  See attached snapshot


- Create an empty  Java project
- Go to the UML project properties
- Check 'Source-Model Synchronization' check box
- Select the Java project from the Java Project
  drop-down list
- Press OK button

- Select the UML project and invoke 'Generate Code'
- Go to the source of 'MyClass' Interface element

   Select 'MyInterface' interface name after 'implements' word
   and invoke 'Refactor|Rename' from popup menu
  
  See attached snapshot
 
  The dialog with errors pops up:
  The original element being refactored is not available. It was deleted
  or significantly changed. Usages  cannot be collected.