Add javadoc

connectivity/model/src/main/java/org/eclipse/ditto/connectivity/model/mqtt/MessageExpiryInterval.java

@@ -24,7 +24,7 @@
  * The maximum seconds is {@value MAX_INTERVAL_SECONDS}.
  */
 @Immutable
-public class MessageExpiryInterval {
+public final class MessageExpiryInterval {
 
     public static final long MIN_INTERVAL_SECONDS = 1L;
 
@@ -36,6 +36,14 @@ private MessageExpiryInterval(@Nullable final Long seconds) {
         this.seconds = seconds;
     }
 
+    /**
+     * Returns an instance of {@code MessageExpiryInterval} for the specified interval.
+     *
+     * @param seconds the message expiry interval duration in seconds. The value must be between
+     * {@value #MIN_INTERVAL_SECONDS} and {@value #MAX_INTERVAL_SECONDS} (both inclusive).
+     * @return the MessageExpiryInterval for interval of {@code seconds}.
+     * @throws IllegalMessageExpiryIntervalSecondsException if the seconds is less than {@value MIN_INTERVAL_SECONDS} or greater than {@value #MAX_INTERVAL_SECONDS}.
+     */
     public static MessageExpiryInterval of(final long seconds)
             throws IllegalMessageExpiryIntervalSecondsException {
         if (seconds < MIN_INTERVAL_SECONDS || seconds > MAX_INTERVAL_SECONDS) {
@@ -50,10 +58,20 @@ public static MessageExpiryInterval of(final long seconds)
         return new MessageExpiryInterval(seconds);
     }
 
+    /**
+     * Returns an instance of the empty {@code MessageExpiryInterval}.
+     *
+     * @return the empty message expiry interval.
+     */
     public static MessageExpiryInterval empty() {
         return new MessageExpiryInterval(null);
     }
 
+    /**
+     * Returns message expiry interval seconds.
+     *
+     * @return optional count of seconds in the interval.
+     */
     public OptionalLong getAsOptionalLong() {
         return seconds != null ?
                 OptionalLong.of(seconds) :

connectivity/service/src/main/java/org/eclipse/ditto/connectivity/service/messaging/mqtt/hivemq/message/publish/GenericMqttPublish.java

@@ -112,6 +112,11 @@ public static Builder builder(final MqttTopic mqttTopic, final MqttQos mqttQos)
      */
     public abstract boolean isRetain();
 
+    /**
+     * Returns expiry interval for this Publish message.
+     *
+     * @return message expiry interval.
+     */
     public abstract MessageExpiryInterval getMessageExpiryInterval();
 
     public abstract Optional<ByteBuffer> getCorrelationData();
@@ -238,6 +243,12 @@ public Builder retain(final boolean retain) {
             return this;
         }
 
+        /**
+         * Sets message expiry interval.
+         *
+         * @param messageExpiryInterval expiry interval of the Publish
+         * @return this Builder instance for method chaining.
+         */
         public Builder messageExpiryInterval(final MessageExpiryInterval messageExpiryInterval) {
             this.messageExpiryInterval = messageExpiryInterval;
             return this;