A container to store the actual latest sequence Id reserved for a given id generator and table name.
        /// <summary>
        /// Tries to write the current sequence value for a table.
        /// </summary>
        /// <param name="syncData">The table name and current value for the sequence.  Also an ETag representing
        /// the latest reserved value retrieved.  The ETag must match the curent stored value for the update/write
        /// to succeed.</param>
        /// <returns></returns>
        public bool TryWrite(OptimisticSyncData syncData)
        {
            var sequence = SequenceTableProxy.Get(syncData.TableName.GetValidPartitionKey(), syncData.TableName.GetValidRowKey()) ??
                           CreateSequenceFromSchema(syncData.TableName);

            if (sequence.ETag != syncData.ConcurrencyKey)
                return false; //caller can get data again and attempt a retry.

            sequence.Entity.Properties[PropertyFinalCachedId].StringValue = syncData.Data;
            SequenceTableProxy.Update(sequence);
            return true;
        }