Update the MessageAttachmentContainer model to omit empty fields

Author: Viktor Pelepiak

slack-base/src/main/java/com/hubspot/slack/client/models/interaction/MessageAttachmentContainerIF.java

@@ -1,5 +1,6 @@
 package com.hubspot.slack.client.models.interaction;
 
+import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.PropertyNamingStrategies;
 import com.fasterxml.jackson.databind.annotation.JsonNaming;
@@ -11,6 +12,7 @@
 @Value.Immutable
 @HubSpotStyle
 @JsonNaming(PropertyNamingStrategies.SnakeCaseStrategy.class)
+@JsonInclude(JsonInclude.Include.NON_EMPTY)
 public interface MessageAttachmentContainerIF extends Container {
   String getMessageTs();