Bug 187796 [KeyBindings] IBindingService cannot return best active bindings for a ParameterizedCommand
IBindingService only supports getBestActiveBindingFor(final String commandId) ... there must be an equivalent method for ParameterizedCommands PW
bundles/org.eclipse.jface/src/org/eclipse/jface/bindings/BindingManager.java
*            The command manager that will support this binding manager.
	 *            This value must not be <code>null</code>.
	 */
	public BindingManager(final ContextManager contextManager,
			final CommandManager commandManager) {
		if (contextManager == null) {
			throw new NullPointerException(
					"A binding manager requires a context manager"); 
		}
		if (commandManager == null) {
			throw new NullPointerException(
					"A binding manager requires a command manager"); 
		}
		this.contextManager = contextManager;
		contextManager.addContextManagerListener(this);
		this.commandManager = commandManager;
	}
	/**
	 * <p>
	 * Adds a single new binding to the existing array of bindings. If the array
	 * is currently <code>null</code>, then a new array is created and this
	 * binding is added to it. This method does not detect duplicates.
	 * </p>
	 * <p>
	 * This method completes in amortized <code>O(1)</code>.
	 * </p>
	 * 
	 * @param binding
	 *            The binding to be added; must not be <code>null</code>.
	 */