Change the value of the field that has the RId annotation. Since the
liveObjectId is encoded as a part of the name of the underlying RMap,
this action will result in renaming the underlying RMap based on the
naming scheme specified in the REntity annotation of the instance class.
Returns true if this object holds no other values apart from the field
annotated with RId. This involves in invoking the isExist() method on the
underlying RMap. Since the field with RId annotation is encoded in the
name of the underlying RMap, so to ensure the map exist in redis, set a
non null value to any of the other fields.