Currently, the Time definition of the ShardRegistry has some flaws:

• no total order: potential causal consistency breakage (timeInStore overwriting a newer topologyTime).
• Null topologyTime cause the topologyTime component to be ignored. In the absence of forceReloads or rsmIncrements, the topologyTime in VectorClock never advances timeInStore.

The Time definition should be reworked to address these issues.