Some union types have string before other datatypes

[dplore]

When a (unconstrained) string appears before other types in a union, the other types cannot be properly used which may cause unintended side effects.

This issue tracks finding these occurrences and fixing them by reordering the union.

See also RFC 6020 Section 9.12

   When a string representing a union data type is validated, the string
   is validated against each member type, in the order they are
   specified in the "type" statement, until a match is found.