TableEntityTimestamp Property
The Timestamp property is a DateTime value that is maintained on the server side to record the time an entity was last modified.
The Table service uses the Timestamp property internally to provide optimistic concurrency. The value of Timestamp is a monotonically increasing value,
meaning that each time the entity is modified, the value of Timestamp increases for that entity.
This property should not be set on insert or update operations (the value will be ignored).