105                 ((Map.Entry)(m.entrySet().iterator().next())).setValue(v2);
 106                 assertSame(v2, m.get(k));
 107                 assertTrue(m.containsKey(k));
 108                 assertTrue(m.containsValue(v2));
 109                 assertFalse(m.containsValue(v1));
 110             } else {
 111                 assertThrows(UnsupportedOperationException.class,
 112                              () -> ((Map.Entry)(m.entrySet().iterator().next())).setValue(v2));
 113             }
 114         }
 115     }
 116 
 117     /**
 118      * Tests and extends the scenario reported in
 119      * https://bugs.openjdk.java.net/browse/JDK-8186171
 120      * HashMap: Entry.setValue may not work after Iterator.remove() called for previous entries
 121      * ant -Djsr166.tckTestClass=HashMapTest -Djsr166.methodFilter=testBug8186171 -Djsr166.runsPerTest=1000 tck
 122      */
 123     public void testBug8186171() {
 124         if (!impl.supportsSetValue()) return;

 125         final ThreadLocalRandom rnd = ThreadLocalRandom.current();
 126         final boolean permitsNullValues = impl.permitsNullValues();
 127         final Object v1 = (permitsNullValues && rnd.nextBoolean())
 128             ? null : impl.makeValue(1);
 129         final Object v2 = (permitsNullValues && rnd.nextBoolean() && v1 != null)
 130             ? null : impl.makeValue(2);
 131 
 132         // If true, always lands in first bucket in hash tables.
 133         final boolean poorHash = rnd.nextBoolean();
 134         class Key implements Comparable<Key> {
 135             final int i;
 136             Key(int i) { this.i = i; }
 137             public int hashCode() { return poorHash ? 0 : super.hashCode(); }
 138             public int compareTo(Key x) {
 139                 return Integer.compare(this.i, x.i);
 140             }
 141         }
 142 
 143         // Both HashMap and ConcurrentHashMap have:
 144         // TREEIFY_THRESHOLD = 8; UNTREEIFY_THRESHOLD = 6;

 105                 ((Map.Entry)(m.entrySet().iterator().next())).setValue(v2);
 106                 assertSame(v2, m.get(k));
 107                 assertTrue(m.containsKey(k));
 108                 assertTrue(m.containsValue(v2));
 109                 assertFalse(m.containsValue(v1));
 110             } else {
 111                 assertThrows(UnsupportedOperationException.class,
 112                              () -> ((Map.Entry)(m.entrySet().iterator().next())).setValue(v2));
 113             }
 114         }
 115     }
 116 
 117     /**
 118      * Tests and extends the scenario reported in
 119      * https://bugs.openjdk.java.net/browse/JDK-8186171
 120      * HashMap: Entry.setValue may not work after Iterator.remove() called for previous entries
 121      * ant -Djsr166.tckTestClass=HashMapTest -Djsr166.methodFilter=testBug8186171 -Djsr166.runsPerTest=1000 tck
 122      */
 123     public void testBug8186171() {
 124         if (!impl.supportsSetValue()) return;
 125         if (!atLeastJava10()) return; // jdk9 is no longer maintained
 126         final ThreadLocalRandom rnd = ThreadLocalRandom.current();
 127         final boolean permitsNullValues = impl.permitsNullValues();
 128         final Object v1 = (permitsNullValues && rnd.nextBoolean())
 129             ? null : impl.makeValue(1);
 130         final Object v2 = (permitsNullValues && rnd.nextBoolean() && v1 != null)
 131             ? null : impl.makeValue(2);
 132 
 133         // If true, always lands in first bucket in hash tables.
 134         final boolean poorHash = rnd.nextBoolean();
 135         class Key implements Comparable<Key> {
 136             final int i;
 137             Key(int i) { this.i = i; }
 138             public int hashCode() { return poorHash ? 0 : super.hashCode(); }
 139             public int compareTo(Key x) {
 140                 return Integer.compare(this.i, x.i);
 141             }
 142         }
 143 
 144         // Both HashMap and ConcurrentHashMap have:
 145         // TREEIFY_THRESHOLD = 8; UNTREEIFY_THRESHOLD = 6;