This is to avoid compilation issues after class
renamed in lsp4e.
If lsp4e undoes the rename as requested in this bug:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=549859
Then this commit can/should be reverted.
- add parameter to 'addClasspathListener' to request
batched events.
- Create a single SendClasspathNotificationsJob that
processes classpath notifications in batches.