Fix txn_blocked_by order

Author: belliottsmith

src/java/org/apache/cassandra/db/virtual/AccordDebugKeyspace.java

@@ -2089,7 +2089,7 @@ protected TxnBlockedByTable()
                         "  blocked_by_txn_id 'TxnIdUtf8Type',\n" +
                         "  save_status text,\n" +
                         "  execute_at text,\n" +
-                        "  PRIMARY KEY (txn_id, command_store_id, depth, blocked_by_key, blocked_by_txn_id)" +
+                        "  PRIMARY KEY (txn_id, depth, command_store_id, blocked_by_txn_id, blocked_by_key)" +
                         ')', TxnIdUtf8Type.instance), BEST_EFFORT, ASC);
         }
 

src/java/org/apache/cassandra/service/accord/DebugBlockedTxns.java

@@ -96,8 +96,14 @@ public int compareTo(Txn that)
             int c = Integer.compare(this.commandStoreId, that.commandStoreId);
             if (c == 0) c = Integer.compare(this.depth, that.depth);
             if (c == 0) c = this.txnId.compareTo(that.txnId);
+            if (c == 0) c = this.blockedViaKeyString().compareTo(that.blockedViaKeyString());
             return c;
         }
+
+        private String blockedViaKeyString()
+        {
+            return blockedViaKey == null ? "" : blockedViaKey.toString();
+        }
     }
 
     final IAccordService service;