This is a problem in the prototype for jsr14 generics:

frog$ cat -n T.java
     1 interface Iterator<E> {
     2 }
     3
     4 class Set<E> {
     5 Iterator<E> iterator() { return null; }
     6 }
     7
     8 interface Map<K,V> {
     9 public interface Entry<K,V> {
    10 }
    11 public Set<Entry<K,V>> entrySet();
    12 }
    13
    14 class Hashtable<K,V> implements Map<K,V> {
    15 public Set<Entry<K,V>> entrySet() { return null; }
    16
    17 public synchronized String toString() {
    18 Iterator<Map.Entry<K,V>> it = entrySet().iterator();
    19 }
    20 }
frog$ make
/java/jdk/ws/tools/jsr14/build/solaris-sparc/bin/javac -gj *.java
T.java:18: incompatible types
found : Iterator<Map<K,V>.Entry<K,V>>
required: Iterator<Map.Entry<K,V>>
        Iterator<Map.Entry<K,V>> it = entrySet().iterator();
                                                         ^
1 error
*** Error code 1
make: Fatal error: Command failed for target `all'
frog$