Add JSON validation only?

Is your feature request related to a problem? Please describe.
Not a problem. just a useful function..

Describe the solution you'd like
A function DeserializationError error = deserializeJson(json) that just reports if the input JSON is a valid JSON.

Describe alternatives you've considered
I do:

  StaticJsonDocument<0> emptyDoc;
  StaticJsonDocument<0> filter;

  DeserializationError error = deserializeJson(emptyDoc, json, DeserializationOption::Filter(filter));

and that does exactly what I want. But I depend on undefined semantics: keys not present in the filter might as well be skipped instead of parsed, but it seems they are parsed too.

Additional context
None. It is not a big deal, the above alternative is also OK.