Подскажите, какое значение должно быть у типа Date в конструкторе?

...
private String numberContract;
    private Date dataStart;
    private DecimalFormat price;
    private Integer quantity;
    private Date dataEndRent;
    private Date dataEndPrice;
....
 
public Contract() {
        this.numberContract = "Undefined";
        this.dataStart = ;
        this.price =  null;
        this.quantity = 0;
        this.dataEndRent = null;
        this.dataEndPrice = null;
    }

Date date = new Date();
DecimalFormat df =  new  DecimalFormat();

type Exception report
messageInternal Server Error
descriptionThe server encountered an internal error that prevented it from fulfilling this request.
exception
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.orm.hibernate3.HibernateSystemException: could not deserialize; nested exception is org.hibernate.type.SerializationException: could not deserialize
root cause
org.springframework.orm.hibernate3.HibernateSystemException: could not deserialize; nested exception is org.hibernate.type.SerializationException: could not deserialize
root cause
org.hibernate.type.SerializationException: could not deserialize
root cause
java.io.StreamCorruptedException: invalid stream header: 362E3030

private DecimalFormat price;
...
this.price = new  DecimalFormat("##,###,##0.00");
...