A DESCRIPTION OF THE PROBLEM :
In the second code example of <code>Collections.synchronizedSortedMap</code> is the variable <code>s</code> and not <code>s2</code> used.

That's not really a problem. :-) But I hope I can make the documentation better.

Greetings
Markus Wolf

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
synchronizedSortedMap

      ...
  Set s2 = m2.keySet(); // Needn't be in synchronized block
      ...
  synchronized (m) { // Synchronizing on m, not m2 or s2!
      Iterator i = s2.iterator(); // Must be in synchronized block
      ...
ACTUAL -
synchronizedSortedMap

      ...
  Set s2 = m2.keySet(); // Needn't be in synchronized block
      ...
  synchronized (m) { // Synchronizing on m, not m2 or s2!
      Iterator i = s.iterator(); // Must be in synchronized block
      ...

URL OF FAULTY DOCUMENTATION :
http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html#synchronizedSortedMap%28java.util.SortedMap%29