Bug 127861 [DataBinding] Mark API provisional
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/Updatable.java
if (!changeListeners.contains(changeListener)) {
			changeListeners.add(changeListener);
		}
		
		 
		
		
		
		
		
		if (changeListeners.size() > 32) {
			Collection newListeners = new HashSet();
			  
			newListeners.addAll(changeListeners);
			changeListeners = newListeners;
		}
	}
	
	/**
	 * Called when the first listener is added to this updatable. Some updatables
	 * may optimize themselves by removing listeners from other object when nobody
	 * is listening to the updatable. Such updatables may use this method to detect
	 * when they need to start tracking changes. 
	 * 
	 * <p>
	 * Important: implementations of this method must not change the current
	 * value of the updatable or fire any property changes. 
	 * </p>
	 */