/** Inserts this entry before the specified existing entry in the list. */
private void addBefore(Entry<K, V> existingEntry) {
after = existingEntry;
before = existingEntry.before;
before.after = this;
after.before = this;
}
/** Removes all of the mappings from this map. The map will be empty after this call returns. */
public void clear() {
super.clear();
header.before = header.after = header;
}
/** Removes this entry from the linked list. */
private void remove() {
before.after = after;
after.before = before;
}
/**
* Called by superclass constructors and pseudoconstructors (clone, readObject) before any entries
* are inserted into the map. Initializes the chain.
*/
void init() {
header = new Entry<>(-1, null, null, null, keyEquality);
header.before = header.after = header;
}