"http://repo.mysql.com/apt/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8C718D3B5072E1F5" code example

Example: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6494C6D6997C215E