Passing check arguments to a service object

Hello there! and i hope you can help a newbie with something…

i have an imap check plugin to check an inbox count and email age.

The query works fine in the plugins file and looks something like that:

./check_imap --hostname ‘myhost’ --username ‘myuser’ --password ‘mypass’ --ssl

upon initializing this check as a service, i failed to know how to enter the “–ssl” flag as an argument to my service. All other arguments have values and are initialized easily like:
vars.HOSTNAME = “myhost”
vars.USERNAME = “myuser”
vars.PASSWORD = “mypass”

however, the --ssl flag has no value

i tried passing it as a boolean var or as an empty one with no luck.
so vars.ssl = “true”
& vars.ssl = “”
didn’t bring me any success.

What i tried also:

I checked the help --h output of the check but only found the possible flags.

From icinga web interface i checked the options available for this command but failed to find the ssl one.

Any idea how to pass this flag to my object?