Add comments, revert TTL change at AckMessage as it has no effect anyway

p2p/src/main/java/bisq/network/p2p/AckMessage.java

@@ -34,6 +34,10 @@
 
 import javax.annotation.Nullable;
 
+// TODO ExpirablePayload has no effect here as it is either a direct msg or packed into MailboxStoragePayload
+// We could extend the TTL by setting the TTL in MailboxStoragePayload from the type of msg which gets into the
+// SealedAndSigned data.
+
 // We exclude uid from hashcode and equals to detect duplicate entries of the same AckMessage
 @EqualsAndHashCode(callSuper = true, exclude = {"uid"})
 @Value
@@ -145,9 +149,10 @@ public static AckMessage fromProto(protobuf.AckMessage proto, int messageVersion
     // API
     ///////////////////////////////////////////////////////////////////////////////////////////
 
+    //TODO has no effect, see comment at class definition
     @Override
     public long getTTL() {
-        return TimeUnit.DAYS.toMillis(2);
+        return TimeUnit.DAYS.toMillis(10);
     }
 
     @Override

p2p/src/main/java/bisq/network/p2p/storage/payload/MailboxStoragePayload.java

@@ -47,6 +47,7 @@
  * That is the typical requirement for a mailbox like system.
  * <p/>
  * Typical payloads are trade or dispute network_messages to be stored when the peer is offline.
+ * Size depends on payload but typical size is 2000-3000 bytes
  */
 @Getter
 @EqualsAndHashCode