Some countries do not have states, so this can fail if null is passed for an empty country

(cherry picked from commit a4a1e51)

Author: kendallb

openapi.yaml

@@ -4591,6 +4591,7 @@ components:
         state_province:
           type: string
           minLength: 1
+          nullable: true
           example: Manitoba
           description: >
             The state or province.  For some countries (including the U.S.) only