Fix trailing whitespaces in documentation comments and remove unneces…

…sary statements.

src/main/java/cool/mqtt/hooks/MqttMessage.java

@@ -8,17 +8,17 @@ public interface MqttMessage {
 
   /**
    * Gets the name of the topic to which this message is being published.
-   * 
+   *
    * @return the topic name
    */
   String getTopicName();
 
   /**
    * Gets the <i>Application Message</i> carried by this message.
-   * 
+   *
    * <p>The MQTT Protocol Specifications defines the Application Message as the payload of the
    * {@code PUBLISH} Control Packet.
-   * 
+   *
    * @return the byte array containing the <i>Application Message</i> info
    */
   byte[] getApplicationMessage();
@@ -36,19 +36,19 @@ public interface MqttMessage {
    * <p>The retain flag specifies whether the MQTT broker must store this message, in order to be
    * immediately delivered to future clients as they subscribe to matching topics.
    *
-   * @return {@code true} if the <i>retained</i> flag is set, {@code false} otherwise
+   * @return {@code true} if the <i>retained</i> flag is set
    */
   boolean isRetained();
 
   /**
    * Gets the <i>duplicate</i> flag of this message.
-   * 
+   *
    * <p>Only for messages with {@code QoS level > 0}, the duplicate flag indicates that this message
    * might have been re-sent because not acknowledged in an earlier attempt.
-   * 
+   *
    * <p>In case of {@link QoS#AT_MOST_ONCE} level, this method always returns {@code false}.
-   * 
-   * @return {@code true} if the <i>duplicate</i> flag is set, {@code false} otherwise
+   *
+   * @return {@code true} if the <i>duplicate</i> flag is set
    */
   boolean isDuplicate();