Builder Pattern compatible with Errai Marshalling

OrientationSensorReading.java

package ca.fuerth.demo.client.shared;

import java.util.Date;

import org.jboss.errai.common.client.api.annotations.Portable;
import org.jboss.errai.marshalling.client.api.annotations.MapsTo;

@Portable
public final class OrientationSensorReading {

  private final Date observationTime;
  private final double x;
  private final double y;
  private final double z;

  public OrientationSensorReading(
      @MapsTo("observationTime") Date observationTime,
      @MapsTo("x") double x,
      @MapsTo("y") double y,
      @MapsTo("z") double z) {
    this.observationTime = new Date(observationTime.getTime());
    this.x = x;
    this.y = y;
    this.z = z;
  }

  public Date getObservationTime() { return new Date(observationTime.getTime()); }
  public double getX() { return x; }
  public double getY() { return y; }
  public double getZ() { return z; }

  @Override
  public String toString() {
    return "OrientationSensorReading [observationTime=" + observationTime
        + ", x=" + x + ", y=" + y + ", z=" + z + "]";
  }

  public static class Builder {
    private Date observationTime = new Date();
    private double x;
    private double y;
    private double z;

    public Builder time(Date time) { this.observationTime = time; return this; }
    public Builder x(double x) { this.x = x; return this; }
    public Builder y(double y) { this.y = y; return this; }
    public Builder z(double z) { this.z = z; return this; }

    public OrientationSensorReading build() {
      return new OrientationSensorReading(observationTime, x, y, z);
    }
  }
}