these are iso8601 compliant time stamps there is 660kb library for parsing strings like these called joda time gson is a json parser not a timestamp parser, you can take a look at this answer for converting iso8601 time stamps to java.util.date , both the question and the answer explain in detail how to do this.
If the format of the date string isn't going to change then for now you could try this.
SimpleDateFormat ISO8601DATEFORMAT = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ", Locale.US);
Date date = ISO8601DATEFORMAT.parse(date);
I personally had been using the format yyyy-MM-dd'T'HH:mm:ss.SSSZ
for quite a while to parse iso8601 timestamps, but have now moved to using joda time.