refactor: revert `keys` change

common/src/main/java/net/william278/husksync/redis/RedisManager.java

@@ -299,20 +299,16 @@ public class RedisManager extends JedisPubSub {
     public void clearUsersCheckedOutOnServer() {
         final String keyFormat = String.format("%s*", RedisKeyType.DATA_CHECKOUT.getKeyPrefix(clusterId));
         try (Jedis jedis = jedisPool.getResource()) {
-            final Set<String> keys = Sets.newHashSet();
-
-            // Scan for keys
-            String nextCursor;
-            do {
-                final ScanResult<String> scanResult = jedis.scan(keyFormat, new ScanParams().match(keyFormat));
-                keys.addAll(scanResult.getResult());
-                nextCursor = scanResult.getCursor();
-            } while (!nextCursor.equals("0"));
-
-            // Delete matched keys
-            jedis.del(keys.stream()
-                    .filter(k -> jedis.get(k).equals(plugin.getServerName()))
-                    .toArray(String[]::new));
+            final Set<String> keys = jedis.keys(keyFormat);
+            if (keys == null) {
+                plugin.log(Level.WARNING, "Checkout key returned null from Redis during clearing");
+                return;
+            }
+            for (String key : keys) {
+                if (jedis.get(key).equals(plugin.getServerName())) {
+                    jedis.del(key);
+                }
+            }
         } catch (Throwable e) {
             plugin.log(Level.SEVERE, "An exception occurred clearing this server's checkout keys on Redis", e);
         }