(as found by errorprone)
The code below is bogus because eras[i] is an Era while eraName is a String, and so it looks like getEra always returns null, which further suggests this method is never tested.

    public Era getEra(String eraName) {
        if (eras != null) {
            for (int i = 0; i < eras.length; i++) {
                if (eras[i].equals(eraName)) {
                    return eras[i];
                }
            }
        }
        return null;
    }