import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.nio.charset.Charset;

public class Main extends HttpServlet {
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
      throws ServletException, IOException {
    resp.getWriter().print("Hello from Java! Charset: " + Charset.defaultCharset());
  }
}

@@ -297,16 +297,18 @@
 n %7B%0A    
+//
 resp.get
@@ -380,14 +380,57 @@
 set());%0A
+    resp.sendRedirect(%22/html/index.html%22);%0A
   %7D%0A%7D%0A

Update Main.java