[reSIProcate] What is the difference between PlainContents and GenericContents classes ?

["priya g. ranjan" <priyaranjan@xxxxxxxxxxx>]

Hello, 
 
I am looking at the reSIProcate parsing code design. I did not understand the 
difference in the classes - PlainContents and GenericContents. The behavior of 
the two classes seemed identical, and there were no other sub-classes 
inheriting from PlainContents. 
 
Thanks,
- Ranjan