-20428 URI SPECIFIED IN THE XMLSCHEMA CLAUSE IS AN EMPTY STRING.

Explanation
Either the target namespace URI that was specified
following the URI keyword or the schema location URI that was specified
following the LOCATION keyword is an empty string.

System action
The statement cannot be processed.

Programmer response
Make sure that every target namespace URI
and every schema location URI in the XMLSCHEMA clause is a valid URI,
and that it is not an empty string.

SQLSTATE
 428GV