Trying to do case insensitive comparison in web api

I am writing a web-api to query our employee table.  To that end,  I want to be able to query an employee based on a case-insensitive search of the email address.

Here's my queryFilter that I am using...

filter: a!queryFilter(
field: "Email",
operator: "=",
value: upper(http!request.queryParameters.emailAddress)
)

Note that at the moment, though I am converting the incoming parameter to upper, what I was wanting to do is [somehow] produce a match between the Email field and the http!request.queryParameters.emailAddress parameter regardless of any differences in case.

So, if the EMPLOYEE.Email field has "Joe.Smith@myorg.com.au", then I want this to match against http!request.queryParameters.emailAddress values of:

"joe.smith@myorg.com.au" or "JOE.SMITH@myorg.com.au" or "JOE.SMITH@MYORG.COM.AU" and so on.

Is there a way to do this in Appian?  What I'm looking for is either a comparison operator that does a case-insensitive comparison, or some way to [also] convert the Email field to upper to match the upper'd value of http!request.queryParameters.emailAddress.

Any help with this is much appreciated.  This *should* be quite simple, but I've been struggling to find a way to do it.

thanks heaps,

David.