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
* not yet computed, then this completes in <code>O(nn)</code>, where
	 * <code>n</code> is the number of bindings.
	 * </p>
	 * 
	 * @return The map of triggers (<code>TriggerSequence</code>) to
	 *         bindings (<code>Binding</code>) which are currently active.
	 *         This value may be <code>null</code> if there are no active
	 *         bindings, and it may be empty.
	 */
	private final Map getActiveBindings() {
		if (activeBindings == null) {
			recomputeBindings();
		}
		return activeBindings;
	}
	/**
	 * <p>
	 * Returns the active bindings indexed by command identifier. The caller
	 * must not modify the returned map.
	 * </p>
	 * <p>
	 * This method completes in <code>O(1)</code>. If the active bindings are
	 * not yet computed, then this completes in <code>O(nn)</code>, where
	 * <code>n</code> is the number of bindings.
	 * </p>
	 * 
	 * @return The map of fully-parameterized commands (<code>ParameterizedCommand</code>)
	 *         to triggers (<code>TriggerSequence</code>) which are
	 *         currently active. This value may be <code>null</code> if there
	 *         are no active bindings, and it may be empty.