WAF Rule to block all http/https traffic using Azure Application gateway

When configuring WAFs I'm used to configuring the lowest priority rule to block all inbound http/https traffic. I then add higher priority allow rules to open up the access I require.

I cant see how I can create a "block all" rule in the Azure Application Gateway's WAF custom rules?

So.. this is how you can do this (apologies the config is in terraform format)

custom_rules { name = "blockAllPaths" priority = 90 rule_type = "MatchRule"

match_conditions {
  match_variables {
    variable_name = "RequestUri"
  }
  operator           = "BeginsWith"
  negation_condition = false
  match_values       = ["/"]
}

action = "Block"

}