[ongeki,api] support ongeki rival

src/main/java/icu/samnyan/aqua/sega/util/jackson/UserIdSerializer.java

@@ -0,0 +1,27 @@
+package icu.samnyan.aqua.sega.util.jackson;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.ser.std.StdSerializer;
+import icu.samnyan.aqua.sega.ongeki.model.userdata.UserData;
+
+import java.io.IOException;
+
+/**
+ * @author samnyan (privateamusement@protonmail.com)
+ */
+public class UserIdSerializer extends StdSerializer<UserData> {
+
+    public UserIdSerializer() {
+        this(null);
+    }
+
+    public UserIdSerializer(Class<UserData> t) {
+        super(t);
+    }
+
+    @Override
+    public void serialize(UserData value, JsonGenerator gen, SerializerProvider provider) throws IOException {
+        gen.writeNumber(value.getCard().getExtId());
+    }
+}