@Override
      public void doSave(OutputStream outputStream, Map< ? , ? > options)
            throws IOException
{
      MyModel myModel=...;
      TransactionalEditingDomain editingDomain = getEditingDomain(resourceSet);

      final CommandStack commandStack = editingDomain.getCommandStack();
      commandStack.execute(new RecordingCommand(editingDomain)
      {
         @Override
         protected void doExecute()
         {
              //My custom Changes
              myModel.setCustomName("");
          
            }
         }
      });

   super.save(outputStream, options);
}