Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend.

[giantpanda]

Full Error: Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 8107 (aptd)

What was being done at the time?
$ sudo apt install openjdk-14-jre-headless

Resolution.

This is one of those errors where the answer is in the error, "It is held by process 8107 (aptd)" wait for the process to finish, or free it up if not required and then run your command again.