Fix build

Author: Viktor Pelepiak

slack-base/src/main/java/com/hubspot/slack/client/methods/params/chat/ChatUnfurlParamsIF.java

@@ -18,7 +18,6 @@
 @Immutable
 @HubSpotStyle
 @JsonNaming(SnakeCaseStrategy.class)
-@JsonInclude(JsonInclude.Include.NON_EMPTY)
 public interface ChatUnfurlParamsIF extends HasChannel {
   @Override
   @JsonProperty("channel")
@@ -35,5 +34,6 @@ public interface ChatUnfurlParamsIF extends HasChannel {
 
   Optional<URI> getUserAuthUrl();
 
+  @JsonInclude(JsonInclude.Include.NON_EMPTY)
   Optional<Metadata> getMetadata();
 }

slack-base/src/test/resources/chat_unfurl_params_using_attachment.json

@@ -26,6 +26,5 @@
   },
   "user_auth_message": null,
   "user_auth_url": null,
-  "is_user_auth_required": null,
-  "metadata" : null
+  "is_user_auth_required": null
 }

slack-base/src/test/resources/chat_unfurl_params_using_block.json

@@ -21,6 +21,5 @@
   },
   "user_auth_message": null,
   "user_auth_url": null,
-  "is_user_auth_required": null,
-  "metadata" : null
+  "is_user_auth_required": null
 }