Not use lombok

User.java

public class User implements java.io.Serializable{
  
  public String username;
  public String email;
  
  public String getUsername() {
    return username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

  public String getEmail() {
    return email;
  }

  public void setEmail(String email) {
    this.email = email;
  }
}