Requires exactly one validator to pass.
Rejects ambiguity as well as absence: matching no validator is unsatisfiable, matching several is ambiguous, and both are reported as a bare message telling the two apart.
The type of the validated value
The mutually exclusive validators; omitted or disabled validators are ignored
A validator reporting a violation unless exactly one enabled validator passes
Requires exactly one validator to pass.
Rejects ambiguity as well as absence: matching no validator is unsatisfiable, matching several is ambiguous, and both are reported as a bare message telling the two apart.