Replacing the protocol from http to https for certain domain

you can use multiple value pair in string map command:

when HTTP_RESPONSE {
    if { [HTTP::header exists Location] } {
        HTTP::header replace [string map -nocase {"http://www.example.com" "https://www.example.com" "http://www2.example.com" "https://www2.example.com" "http://www3.example.com" "https://www3.example.com" "http://www4.example.com" "https://www4.example.com"} [HTTP::header Location]]
    }
}