\DateTime::ISO8601 is deprecated use RFC3339 instead

Hmm, this would mean a change in the returned format:

public const string DateTimeInterface::ISO8601 = "Y-m-d\\TH:i:sO";
public const string DateTimeInterface::RFC3339 = "Y-m-d\\TH:i:sP";

The only change is the colon (:) between the hours. This is fine for new defaults. Existing configuration should not be affected.

Automatically closed - issue fixed for 2 weeks with no activity.