一个关于Java中SortedMap定义的问题

一个关于Java中SortedMap定义的问题

在SortedMap接口的解释中有这么一段话：

 * 
Note that the ordering maintained by a sorted map (whether or not an
 * explicit comparator is provided) must be consistent with equals if
 * the sorted map is to correctly implement the Map interface.  (See
 * the Comparable interface or Comparator interface for a
 * precise definition of consistent with equals.)  This is so because
 * the Map interface is defined in terms of the equals
 * operation, but a sorted map performs all key comparisons using its
 * compareTo (or compare) method, so two keys that are
 * deemed equal by this method are, from the standpoint of the sorted map,
 * equal.  The behavior of a tree map is well-defined even if its
 * ordering is inconsistent with equals; it just fails to obey the general
 * contract of the Map interface.

请问这段话是什么意思？