Invoking AWS Lambda Authorizer using Function URL

Question

I have implemented an AWS Lambda Authorizer in Java (type=REQUEST). I would like to invoke the lambda using a Function URL. I need to pass the following fields to my Lambda AuthorizerEvent:

• headers
• type (REQUEST)
• methodArn

I am sending the HTTP GET message using Postman. The headers get mapped correctly to the event object. However, type and methodARN are shown as null in the CloudWatch logs and the Function URL returns a 502 Bad Gateway error:

Received AuthorizerEvent(type=null, authorizationToken=null, headers={...}, methodArn=null)

I've tried putting type and methodArn in query parameters, headers and body (even though REQUEST authorizers don't use the body, see here). I also can't find complete documentation outlining how HTTP parameters are mapped to the lambda request event parameters for Authorizer Function URLs.

Any help would be greatly appreciated!