Ultimate irule debug - Capture and investigate

Hi, 

I have this irule installed on my F5 ver 15.1 and it works correctly. When trying to update the version to 17.1.2 when checking the configuration, I get this error

There were warnings:
/Common/iRule_debgug_all:207: warning: [use curly braces to avoid double substitution][$http_request_time]
/Common/iRule_debgug_all:208: warning: [use curly braces to avoid double substitution][$http_response_time]
/Common/iRule_debgug_all:209: warning: [use curly braces to avoid double substitution][$http_request_time_release]

this is the irule in F5

 207 log local0.info "uid: $uid - Time to request  (F5 request time) = [expr $http_request_time - $http_request_time_release] (ms)"
208 log local0.info "uid: $uid - Time to response (F5 response time) = [expr $http_response_time - $http_response_time_release] (ms)"
209 log local0.info "uid: $uid - Time to server (server backend process time) = [expr $http_request_time_release - $http_response_time] (ms)"

Can you help me?

Thank´s