Bug 277966 [Databinding] regression: ObservablesManager throws NPE on dispose if one of the observables is already disposed
tests/org.eclipse.jface.tests.databinding/src/org/eclipse/core/tests/databinding/ObservablesManagerTest.java
return null;
		}
		/*
		 * (non-Javadoc)
		 *
		 * @see org.eclipse.core.databinding.observable.value.IObservableValue#removeValueChangeListener(org.eclipse.core.databinding.observable.value.IValueChangeListener)
		 */
		public void removeValueChangeListener(IValueChangeListener listener) {
			
		}
		/*
		 * (non-Javadoc)
		 *
		 * @see org.eclipse.core.databinding.observable.value.IObservableValue#setValue(java.lang.Object)
		 */
		public void setValue(Object value) {
			
		}
		/*
		 * (non-Javadoc)
		 *
		 * @see org.eclipse.core.databinding.observable.IObservable#addChangeListener(org.eclipse.core.databinding.observable.IChangeListener)
		 */
		public void addChangeListener(IChangeListener listener) {
			
		}
		public void addDisposeListener(IDisposeListener listener) {