How to test Flow Service having null child Doc containing a mandatory subfield?


My Flow Service takes input a document similar to this(this is a simplified form):

-FlowInputDoc (Root, Document, Mandatory[Required=true])
– SubDocument1 (Document, Optional[Required=false])
---- Priority1 (Mandatory, String)
---- Age1 (Optional, String)
– SubDocument2 (Document, Optional[Required=false])
---- Priority2 (Mandatory, String)
---- Age2 (Optional String)

Now the subdocuments 1&2 are optional, as I want to test this service by sending only one of either of subdocuments. But when I test it using Run option from Developer, I have to check mark the box accept Empty String values(gives error that Priority is mandatory otherwise) and The other subdocument(whose values I dont specify) is also included with Priority as Empty String value(whereas I dont want the other subdoc to exist at all).
Hope I’m making some sense.

Kindly Help.

One way is to create a test FLOW service that calls the service setting the inputs as desired for your test.