The L2 EVSE I got last month (ClipperCreek LCS-25P) does not come with a rubber cap for the J1772 end. No doubt they expect you to use one of those holsters. I'm waiting for a more permanent mounting of the EVSE before I get a holster for it, but want to protect the J1772 end in the mean time. I did see the same style of protectors as come on the stock Nissan L1 EVSE (silicone I believe), but did not see many sources or decent prices (nothing on Amazon, just one on eBay, and it would take weeks to get here due to being from China). So I decided to wing it with something not intended for this purpose, but that would hopefully still suffice given that the need is just temporary.
I guessed at a size that would just accommodate the extra 'guide rail' at the bottom, and nailed it. It's a snug fit (won't fall off) and is still easily added/removed by hand.
Downside is they only come in packs of eight.