fix StatusServerResponse serialize

src/main/java/mc/protocol/dto/ServerInfo.java

@@ -1,6 +1,7 @@
 package mc.protocol.dto;
 
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.Data;
 import lombok.ToString;
@@ -22,6 +23,7 @@ public class ServerInfo {
     private Text description;
 
     @JsonProperty("favicon")
+    @JsonInclude(JsonInclude.Include.NON_NULL)
     private String faviconBase64;
     
     @Data

src/main/java/mc/protocol/status/server/StatusServerResponse.java

@@ -72,7 +72,7 @@ public class StatusServerResponse implements Packet {
     @Override
     public void writeSelf(NetOutputStream netOutputStream) {
         if (serverInfo == null) {
-            serverInfo = JsonUtils.objectToJson(serverInfo);
+            serverInfo = JsonUtils.objectToJson(serverInfoDto);
         }
 
         netOutputStream.writeString(serverInfo);