A fetch profile item for fetching UIDs.
This inner class extends the FetchProfile.Item
class to add new FetchProfile item types, specific to UIDFolders.
The only item currently defined here is the UID item.
UID is a fetch profile item that can be included in a
FetchProfile during a fetch request to a Folder.
This item indicates that the UIDs for messages in the specified
range are desired to be prefetched.
An example of how a client uses this is below:
FetchProfile fp = new FetchProfile();
fp.add(UIDFolder.FetchProfileItem.UID);
folder.fetch(msgs, fp);