Resize a gbde encypted partition

[l-freebsd at bitpri.de]

Does anyone know if there is a non-destructive way to resize an existing
partition that is encrypted using gbde?

I'm running 11.2-RELEASE on a VM with two disks: ada0 (root and swap)
and ada1 (encrypted data). I've enlarged the second disk from 20GB to
60GB and followed
https://www.freebsd.org/doc/handbook/disks-growing.html.

The gpart step worked fine:

# gpart resize -i 1 ada1
# gpart show ada1
=>       63  125829057  ada1  MBR  (60G)
         63  125829057     1  freebsd  [active]  (60G)

The problem is with growfs:

# growfs ada1s1
=>  growfs: superblock not recognized

# growfs ada1s1.bde
=>  growfs: requested size 20GB is not larger than the current
filesystem size 20GB

I suspect that resizing is not supported with GBDE devices but haven't
found any mention of it in the Handbook or forums. Can somebody confirm?

Cheers, Karl