Bug 262392 [DataBinding] CompositeMap constructor should use this.firstMap
Using EclEmma, I noticed that large portions of BidiObservableMap are not run, indicating a problem in CompositeMap. This needs more thought. I am attaching a patch, it includes one test case but we may want to add more tests.
tests/org.eclipse.jface.tests.databinding/src/org/eclipse/core/tests/databinding/observable/map/CompositeMapTest.java
private WritableSet persons;
	private CompositeMap composedMap;
	protected void setUp() throws Exception {
		super.setUp();
		persons = new WritableSet();
		IObservableMap first = BeansObservables.observeMap(persons,
				SimplePerson.class, "cart");
		composedMap = new CompositeMap(first, new IObservableFactory() {
			public IObservable createObservable(Object target) {
				return BeansObservables.observeMap((IObservableSet) target,
						SimpleCart.class, "numItems");
			}
		});
	}
	public void testAddToFirstMap() {
		MapChangeEventTracker tracker = new MapChangeEventTracker();