Sorry everyone; didn't see that Octopus Tea already posted this workaround. But I am confirming that this workaround works for 1.15.2!
I have found that if, while renaming the item, you press the space key once, you can revert the object back to its original name. Most likely Mojang didn't want to have objects with no name, so that is why they changed it.
Sorry everyone; didn't see that Octopus Tea already posted this workaround. But I am confirming that this workaround works for 1.15.2!