- DOES_NOT_EXIST, // Server with the specified address does not exist
- NOT_SUPPORTED, // Some types of RemoveServer for example Removing the current Leader may not be
- // supported (at least initially)
+
+ /**
+ * For a RemoveServer request, the server to remove does not exist.
+ */
+ DOES_NOT_EXIST,
+
+ /**
+ * The leader could not process the request due to a prior request that timed out while trying to
+ * achieve replication consensus.
+ */
+ PRIOR_REQUEST_CONSENSUS_TIMEOUT,
+
+ /**
+ * An unsupported request, for example removing the leader in a single node cluster.
+ */
+ NOT_SUPPORTED,
+
+ /**
+ * Some part of the request is invalid.
+ */
+ INVALID_REQUEST,