get Uuids
Retrieves the UUIDs of the supplied names from Xenos. Duplicates are filtered from the result and names that could not be found are discarded from the result. Each result includes the moment when the data was fetched from the Mojang API, so that stale data can be identified. The usernames do not have to be in the correct case and the canonical names will also be returned within the result.
The keys of the result map are all lowercase to prevent duplicate entries. Therefore, to retrieve or check the results, all keys have to be submitted in lowercase. That warrants that every name will only be present once.