assertFalse( "keyset: " + keyset + ", should be unmodified. other: " +
other, keyset.retainAll( other ) );
other.remove( keys[5] );
assertTrue( "keyset: " + keyset + ", should be modified. other: " +
other, keyset.retainAll( other ) );
assertFalse( keyset.contains( keys[5] ) );
assertFalse( map.containsKey( keys[5] ) );
assertFalse( map.containsValue( vals[5] ) );
assertTrue( "keyset: " + keyset + ", should contain all in other: " +
other, keyset.containsAll( other ) );