query parameters in play-spoken-text return entire text when empty string is passed

[hsluytergaethje]

When the query parameters (gender, role, relations) in the endpoint /corpora/{corpusname}/plays/{playname}/spoken-text are set to empty string, the entire text is returned just as if the parameter is not set at all. This behaviour seems quite implicit.
Maybe it would be good to differentiate between the parameter not being passed at all and being passed with empty string as value?
Or it be documented that the two cases produce the same result.