sticker_ids, flags for Message/Webhook send request data (#190)

* Add flags to webhook/message send request data

* Add sticker_ids message send request data

* Fix style for WebhookExecuteRequest

src/main/java/discord4j/discordjson/json/MessageCreateRequest.java

@@ -3,7 +3,9 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import discord4j.discordjson.Id;
 import discord4j.discordjson.possible.Possible;
+import java.util.List;
 import org.immutables.value.Value;
 
 @Value.Immutable
@@ -21,4 +23,7 @@ static ImmutableMessageCreateRequest.Builder builder() {
 
     @Deprecated
     Possible<EmbedData> embed();
+
+    @JsonProperty("sticker_ids")
+    Possible<List<Id>> stickerIds();
 }

src/main/java/discord4j/discordjson/json/MessageSendRequestBase.java

@@ -7,6 +7,8 @@
 
 public interface MessageSendRequestBase {
 
+    Possible<Integer> flags();
+
     Possible<String> content();
 
     Possible<Boolean> tts();

src/main/java/discord4j/discordjson/json/WebhookExecuteRequest.java

@@ -22,6 +22,7 @@ static ImmutableWebhookExecuteRequest.Builder builder() {
     Possible<String> threadName();
 
     Possible<String> username();
+
     @JsonProperty("avatar_url")
     Possible<String> avatarUrl();
 }