@iperry It actually is possible, you just need to enable HSTS in the env.properties -
# Configure HSTS (HTTP Strict Transport Security)
# Enabled by default when ssl.on=true
# Sets the Strict-Transport-Security header, web browsers will always connect using HTTPS when they
# see this header and they will cache the result for max-age seconds
ssl.hsts.enabled=true
ssl.hsts.maxAge=31536000
ssl.hsts.includeSubDomains=false
This will only affect browsers, as @Puckfist says HTTP is actually still enabled and you can make REST requests over HTTP using a script for example.
Just bear in mind that the browser will remember the HSTS setting and refuse to connect to HTTP for the specified amount of time after you configure this.