When I decided to test some locked chests, I noticed that a hopper both going in and taking items from a chest with the

{Lock:"My lock"}

tag, don't get blocked by the lock. This removes much useful functionality since hoppers could easily take and steal items from these locked chests.

What I expected to see:
No items being transferred, possibly items would be transferred into hoppers that shared the same

.

What I saw:
Items were transfered and not blocked in any way, any hopper could change the container.

Steps to reproduce:
Take a container that can be locked, use

/setblock ~ ~ ~ chest 0 replace {Lock:"My Lock"}

Put a hopper above and underneath the chest.

Put items in the top hopper

Watch them flow into the bottom hopper, passing through the chest just fine.