fun difference(penultimate: String?, last: String?): Either<Difference>
Looks for changes in two specified versions.
Searches penultimate and last versions in VersionService. If penultimate version is specified then it will be looked up VersionService else will be invoked VersionService.getPenultimateVersionFile. If last version is specified then it will be looked up VersionService else will be invoked VersionService.getLastVersionFile. If at least one file was not found then will be returned Either.Error with appropriate error message otherwise move on.
After all the necessary files have been found, a search is made for changes in this json data. Difference object is the result of search.
penultimate - penultimate version of the API.
last - last version of the API.
Return
The result of comparing two versions.
If all is fun then will be returned Either.Success else will be returned Either.Error with message or exception.