getCachedValue method
Returns a cached value for this validator. Will be passed to validate
Implementation
@override
MustMatchCacheEntry getCachedValue(DogStructure structure, DogStructureField field) {
final selfIndex = structure.fields.indexOf(field);
final otherIndex = structure.indexOfFieldName(otherFieldName)!;
final proxy = structure.proxy;
return MustMatchCacheEntry(
field.name, structure.fields[otherIndex].name, selfIndex, otherIndex, proxy);
}