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
* </p>
	 * 
	 * @return The active locale; never <code>null</code>.
	 */
	public final String getLocale() {
		return locale;
	}
	/**
	 * <p>
	 * Returns all of the possible bindings that start with the given trigger
	 * (but are not equal to the given trigger).
	 * </p>
	 * <p>
	 * This method completes in <code>O(1)</code>. If the bindings aren't
	 * currently computed, then this completes in <code>O(n)</code>, where
	 * <code>n</code> is the number of bindings.
	 * </p>
	 * 
	 * @param trigger
	 *            The prefix to look for; must not be <code>null</code>.
	 * @return A map of triggers (<code>TriggerSequence</code>) to bindings (<code>Binding</code>).
	 *         This map may be empty, but it is never <code>null</code>.
	 */
	public final Map getPartialMatches(final TriggerSequence trigger) {
		final Map partialMatches = (Map) getPrefixTable().get(trigger);
		if (partialMatches == null) {
			return Collections.EMPTY_MAP;
		}
		return partialMatches;
	}