Support Message forwarding data

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

@@ -21,4 +21,7 @@ static ImmutableMessageCreateRequest.Builder builder() {
 
     @Deprecated
     Possible<EmbedData> embed();
+
+    @JsonProperty("message_reference")
+    Possible<MessageReferenceData> messageReference();
 }

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

@@ -76,6 +76,9 @@ static ImmutableMessageData.Builder builder() {
     @JsonProperty("message_reference")
     Possible<MessageReferenceData> messageReference();
 
+    @JsonProperty("message_snapshots")
+    Possible<List<MessageSnapshotsData>> messageSnapshots();
+
     Possible<Integer> flags();
 
     @Deprecated

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

@@ -0,0 +1,18 @@
+package discord4j.discordjson.json;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import org.immutables.value.Value;
+
+@Value.Immutable
+@JsonSerialize(as = ImmutableMessageSnapshotsData.class)
+@JsonDeserialize(as = ImmutableMessageSnapshotsData.class)
+public interface MessageSnapshotsData {
+
+    static ImmutableMessageSnapshotsData.Builder builder() {
+        return ImmutableMessageSnapshotsData.builder();
+    }
+
+    PartialMessageData message();
+
+}