Bug 314847 Command parameters are never cleared
bundles/org.eclipse.e4.core.commands/src/org/eclipse/e4/core/commands/internal/HandlerServiceImpl.java
while (i.hasNext()) {
			Map.Entry entry = (Map.Entry) i.next();
			context.set((String) entry.getKey(), entry.getValue());
		}
		context.set(PARM_MAP, parms);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @seeorg.eclipse.e4.core.commands.EHandlerService#canExecute(org.eclipse.core.commands.
	 * ParameterizedCommand)
	 */
	public boolean canExecute(ParameterizedCommand command) {
		String commandId = command.getId();
		Object handler = lookUpHandler(context, commandId);
		if (handler == null) {
			return false;
		}
		addParmsToContext(command);
		Boolean result = ((Boolean) ContextInjectionFactory.invoke(handler, CanExecute.class,
				context, Boolean.TRUE));
		return result.booleanValue();
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.e4.core.commands.EHandlerService#deactivateHandler(java.lang.String,
	 * java.lang.Object)
	 */
	public void deactivateHandler(String commandId, Object handler) {