Const
A blank value ("" or whitespace, often an unset shell variable or an empty form field) is invalid: the API treats a missing filter as no filter, so a blank filter would silently widen the search or run it unfiltered.
A blank value ("" or whitespace, often an unset shell variable or an empty form field) is invalid: the API treats a missing filter as no filter, so a blank filter would silently widen the search or run it unfiltered.