Minor, fixed checkstyle and find bugs warns

broker/src/main/java/io/moquette/spi/impl/subscriptions/CTrieSubscriptionDirectory.java

@@ -148,9 +148,9 @@ public class CTrieSubscriptionDirectory implements ISubscriptionsDirectory {
      * We roughly follow this theory above, but we allow CNode with no Subscriptions to linger (for now).
      *
      *
-     * @param inode
-     * @param iParent
-     * @return
+     * @param inode inode that handle to the tomb node.
+     * @param iParent inode parent.
+     * @return REPEAT if the this methods wasn't successful or OK.
      */
     public Action cleanTomb(INode inode, INode iParent) {
         CNode updatedCnode = iParent.mainNode().copy();
@@ -225,8 +225,8 @@ public class CTrieSubscriptionDirectory implements ISubscriptionsDirectory {
      * Removes subscription from CTrie, adds TNode when the last client unsubscribes, then calls for cleanTomb in a
      * separate atomic CAS operation.
      *
-     * @param topic
-     * @param clientID
+     * @param topic the subscription's topic to remove.
+     * @param clientID the Id of client owning the subscription.
      */
     @Override
     public void removeSubscription(Topic topic, String clientID) {

broker/src/main/java/io/moquette/spi/impl/subscriptions/Subscription.java

@@ -47,6 +47,9 @@ public final class Subscription implements Serializable {
 
     /**
      * Constructor with undefined maximum QoS
+     *
+     * @param clientId id of client owning this subscription.
+     * @param topicFilter the topic to subscribe to.
      * */
     public Subscription(String clientId, Topic topicFilter) {
         this.requestedQos = null;

broker/src/main/java/io/moquette/spi/impl/subscriptions/Topic.java

@@ -41,6 +41,9 @@ public class Topic implements Serializable {
 
     /**
      * Factory method
+     *
+     * @param s the topic string (es "/a/b").
+     * @return the created Topic instance.
      * */
     public static Topic asTopic(String s) {
         return new Topic(s);