Method compare

src/main/java/gate/util/RBTreeMap.java:1068–1072

Compares two keys using the correct comparison method for this RBTreeMap.

(Object k1, Object k2)

    * Compares two keys using the correct comparison method for this RBTreeMap.
    */
  @SuppressWarnings({"unchecked", "rawtypes"})
  private int compare(Object k1, Object k2) {
    return (comparator==null ? ((Comparable)k1).compareTo(k2)
       : comparator.compare((K)k1, (K)k2));
  }

  /**
    * Test two values  for equality.  Differs from o1.equals(o2) only in