1) Create a WF that uses a custom rest operation like below.

functions:
  - name: myHttpsFunction
    type: custom
    operation: "rest:post:/my-endpoint" 

2) configure the application properties like this:

kogito.sw.functions.myHttpsFunction.host=myhost.whatever.com 

kogito.sw.functions.myHttpsFunction.port=443

 
3) Make the workflow use the function in an arbitrary step

4) When function call is executed, the httpClient is used instead of  httpsClient