Replace the usage of java.util.Date with the java.time.*

We shouldn't use java.util.Date any more, java.time.* is the modern
date/time API.

Unfortunately, the REST response format of this plugin didn't follow the
format for timestamps as in the Gerrit core REST API. To keep the
backward compatibility we now use String instead of Date in the
MessageOfTheDayInfo and make sure to keep the old formatting.

Change-Id: I4e8139e98db34402109aa9ae8258a6f74dc4d807
2 files changed