ConcurrentModificationException: Remove during Loop - Java Common Bug Pattern

It's a common bug that we try to use collection.remove during looping the collection.

For example: in ehcache 2.7.0 getAll method

    public Map

This was fixed in latest version: ehcache 2.10.0 getAll method
Usually we use Iterator> it=map.entrySet().iterator(); then use it.remove() to delete the element.
Here the iterator of the map returned by compoundStore.getAll() may not support remove method. 
That's why ehcache first adds all expired key to a HashSet, then call:

          try {
              elements.keySet().removeAll(expired);
          } catch (UnsupportedOperationException e) {
              elements = new HashMap(elements);
              elements.keySet().removeAll(expired);
          }

Here is the HashSet removeAll method:

     * Note that this implementation will throw an

     * UnsupportedOperationExceptionif the iterator returned by the

     * iteratormethod does not implement the removemethod.

    public boolean removeAll(Collection c) {

        Objects.requireNonNull(c);

        boolean modified = false;

        if (size() > c.size()) { // optimization: different branch based on size diff

            for (Iterator i = c.iterator(); i.hasNext(); )

                modified |= remove(i.next());

        } else {

            for (Iterator i = iterator(); i.hasNext(); ) {

                if (c.contains(i.next())) {

                    i.remove();

                    modified = true;

                }

            }

        }

        return modified;

    }

ehcache 2.10.0 getAll method
public Map

        getAllObserver.begin();
        checkStatus();

        if (disabled) {
            return null;
        }

        if (keys.isEmpty()) {
            getAllObserver.end(GetAllOutcome.ALL_HIT, 0, 0);
            return Collections.EMPTY_MAP;
        }

        Map