Expanding an xen instance partition fails due to missing "growpart"?!

Hello, I would like to expand a partitation on an instance, but for some reason the command growpart does not exist on this instance? I am proceeding as usual according to https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/recognize-expanded-volume-linux.html, and this has also worked for the other instances in the past, only with the current one I fail at point 2c, as the command "growpart" obviously does not exist on my instance?!?

This is the current situation at this instance:

sudo lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT xvda 202:0 0 8G 0 disk -xvda1 202:1 0 5G 0 part / xvdb 202:16 0 15G 0 disk -xvdb1 202:17 0 15G 0 part /IOL

So the xvda drive has already been increased from 5 to 8 GB.

But when I try to enlarge it using growpart, the result looks like this:

sudo growpart /dev/xvda 1 sudo: growpart: command not found

And indeed, there is obviously none:

which growpart /usr/bin/which: no growpart in (/usr/lib64/qt-3.3/bin:/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/ec2-user/bin)

Maybe you can imagine the look on my face when I saw this message? 8:o Where did that go?! Are there alternative ways to increase the partitation to the full drive size without growpart?