Bug 327585 Commands, Handlers, and keybindings should use leaf lookup
bundles/org.eclipse.e4.core.commands/src/org/eclipse/e4/core/commands/internal/HandlerServiceImpl.java
public void activateHandler(String commandId, Object handler) {
		String handlerId = H_ID + commandId;
		context.set(handlerId, handler);
	}
	/**
	 * @param command
	 */
	private void addParmsToContext(ParameterizedCommand command) {
		final Map parms = command.getParameterMap();
		Iterator i = parms.entrySet().iterator();
		while (i.hasNext()) {
			Map.Entry entry = (Map.Entry) i.next();
			context.set((String) entry.getKey(), entry.getValue());
		}
		context.set(PARM_MAP, parms);
	}
	private void removeParmsFromContext(ParameterizedCommand command) {
		if (context == null) {
			return;
		}
		final Map<?, ?> parms = command.getParameterMap();
		Iterator<?> i = parms.entrySet().iterator();
		while (i.hasNext()) {
			Map.Entry<?, ?> entry = (Map.Entry<?, ?>) i.next();
			context.set((String) entry.getKey(), null);
		}
		context.set(PARM_MAP, null);
	}
	/*
	 * (non-Javadoc)