Really basic immutable models for Java/GWT.

Model.java

import static com.google.common.base.Preconditions.checkNotNull;

public class ImmutableModel {
  private final int id;
  private final String label;
  
  public ImmutableModel(int id, String label) {
    this.id = id;
    this.label = checkNotNull(label);
  }
  
  public int getId() {
    return id;
  }
  
  public String getLabel() {
    return label;
  }
  
  public ImmutableModel withId(int newId) {
    return new ImmutableModel(newId, label);
  }
  
  public ImmutableModel withLabel(String newLabel) {
    return new ImmutableModel(id, newLabel);
  }
}