@mikem

You've gone beyond the scope of issue #4402 here, which is only about the pattern parameter. While we could probably stand to improve validation for some of the other parameters, it should probably be more involved than a single special case for the empty string.

Most of these changes change a valid if questionable call to an invalid one, i.e. that add an error case that was not previously an error case. Changing the api like that requires careful thought and justification.

A number of these params are not meant to accept strings at all. In those cases simply checking for an empty string seems wrong. Those cases would be better served by using convert_value, as we do in numerous other calls.

Let's put a hold on this pending further discussion in #4402