The spec for ConcurrentModificationException says:

  "Some Iterator implementations (including those of all the collection
  implementations provided by the JRE) may choose to throw this exception
  if this behavior is detected"

However, several new collections ((EnumSet, CopyOnWriteArrayList, CopyOnWriteArraySet) have "snapshot iterators" that do not throw ConcurrentModificationException under these circumstances. Thus, we should add some "wiggle words" to the above spec. Suggested change:


  "Some Iterator implementations (including those of all the *general purpose*
  collection implementations provided by the JRE) may choose to throw this
  exception if this behavior is detected"

(The asterisks denote added prose, not emphasis; they should not be present
in the documentation.)