Bug 133375 [Viewers] Need access to the element comparer of a tree selection
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/CustomHashtable.java
/**
     * HashMapEntry is an internal class which is used to hold the entries of a Hashtable.
     */
    private static class HashMapEntry {
        Object key, value;
        HashMapEntry next;
        HashMapEntry(Object theKey, Object theValue) {
            key = theKey;
            value = theValue;
        }
    }
    private static final class EmptyEnumerator implements Enumeration {
        public boolean hasMoreElements() {
            return false;
        }
        public Object nextElement() {
            throw new NoSuchElementException();
        }
    }
    private class HashEnumerator implements Enumeration {
        boolean key;
        int start;
        HashMapEntry entry;
        HashEnumerator(boolean isKey) {
            key = isKey;
            start = firstSlot;