Creating an HTTP monitor in CloudFlare without a body

Cloudflare’s resource cloudflare_load_balancer_monitor seems to require BOTH expected_codes and expected_body:
Error: Error applying plan:

1 error occurred:
* cloudflare_load_balancer_monitor.http_monitor: 1 error occurred:
* cloudflare_load_balancer_monitor.http_monitor: expected_body must be set

However, I can manually create one with, say, just the expected_codes if I do it through the portal…