I think you're mis-using the term "datatype". In the case of rows of a dataTable, what you seem to be calling its "datatypes" would actually be the values of the row item's properties. For the list, there are no properties as such, so it's simple the list values you want to display.
I cannot think offhand why what you are proposing wouldn't work as long as the neededResources property of Product was populated with list values. Although it's generally not possible to make an ORM model object serve directly as a JSF backing bean GUI model object, since the JSF bean manager doesn't have the ability to either locate a specific persistence model object instance or to retrieve it and map it.
One thing I do recommend is that instead of a simple EL expression to output the value, use the h:outputText element. It won't solve the problem of getting a value, but it will at least allow JSF to more cleanly integrate that value into its component tree. Plus, of course, add support for stuff like CSS styling.
An IDE is no substitute for an Intelligent Developer.
thank you for your reply. Sorry, that I answer only now.
As i suspected, the way I tried to display the list of strings was right. What I didn't know, is that such a list of an entity-class doesn't get loaded automatically, when an instance of that class does. So, I set the fetchType of that list to 'Eager' and now it gets displayed on my page :)