JPA OneToMany bidirectional relation [EclipseLink-63] error - one-to-many

Question

Please can you help me? In JPA, I try to create a OneToMany bidirectional relation, but I have the following errors :
"[EclipseLink-63] : The instance creation method [entity.OrderLine.], with no parameters, does not exist, or is not accessible.
[EclipseLink-28019] : Deployment of PersistenceUnit [simple-jpaPU] failed. Close all factories for this PersistenceUnit."
There are my entities :
OneToMany Entity :
package entity;
import java.util.*;
import java.io.Serializable;
import javax.persistence.*;
import org.eclipse.persistence.annotations.TimeOfDay;
#Entity
public class Order implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Temporal(TemporalType.TIMESTAMP)
private Date creationDate;
#OneToMany(mappedBy = "o")
private List<OrderLine> orderLines;
public Date getCreationDate() {
return creationDate;
}
public void setCreationDate(Date creationDate) {
this.creationDate = creationDate;
}
public List<OrderLine> getOrderLines() {
return orderLines;
}
public void setOrderLines(ArrayList<OrderLine> orderLines) {
this.orderLines = orderLines;
}
public Order(Date creationDate) {
this.creationDate = creationDate;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
#Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
#Override
public String toString() {
return "entity.Order[ id=" + id + " ]";
}
}
ManyToOne Entity :
package entity;
import java.io.Serializable;
import javax.persistence.*;
#Entity
#Table(name="orderline_table")
public class OrderLine implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String item;
private Double unitPrice;
private Integer quantity;
#ManyToOne
Order o;
public String getItem() {
return item;
}
public void setItem(String item) {
this.item = item;
}
public Double getUnitPrice() {
return unitPrice;
}
public void setUnitPrice(Double unitPrice) {
this.unitPrice = unitPrice;
}
public Integer getQuantity() {
return quantity;
}
public void setQuantity(Integer quantity) {
this.quantity = quantity;
}
public OrderLine(String item, Double unitPrice, Integer quantity) {
this.item = item;
this.unitPrice = unitPrice;
this.quantity = quantity;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
#Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
#Override
public String toString() {
return "entity.OrderLine[ id=" + id + " ]";
}
}

Answer 1

It fails because OrderLine does not have no-arg constructor. It is required as stated in JPA 2.1 specification (Chapter 2.1):
The entity class must have a no-arg constructor. The entity class may have other constructors as well.The no-arg constructor must be public or protected.
Default constructor is not generated because other constructor is given. Problem can be fixed by adding following constructor:
public OrderLine() {
}