title: one to many bidirectional mapping complaining doesn't have a default value error
body: <p>I have got two entity classes.</p>
  
  <pre><code>@Entity
  </code></pre>
  
  <p>public class Employee {</p>
  
  <pre><code>@Id
  @Column(name = "employee_id")
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Integer id;
  private String name;
  
  @OneToMany(cascade = CascadeType.ALL)
  @JoinTable(name = "employee_skill", joinColumns = @JoinColumn(referencedColumnName = "employee_id"), inverseJoinColumns = @JoinColumn(referencedColumnName = "skill_id"))
  private Collection&lt;Skill&gt; listSkill;
  
  public Integer getId() {
      return id;
  }
  
  public void setId(Integer id) {
      this.id = id;
  }
  
  public String getName() {
      return name;
  }
  
  public void setName(String name) {
      this.name = name;
  }
  
  public Collection&lt;Skill&gt; getListSkill() {
      return listSkill;
  }
  
  public void setListSkill(Skill skill) {
      if (listSkill == null) {
          listSkill = new ArrayList&lt;Skill&gt;();
      }
      listSkill.add(skill);
  }
  </code></pre>
  
  <p>}</p>
  
  <pre><code>@Entity
  </code></pre>
  
  <p>public class Skill {</p>
  
  <pre><code>@Id
  @Column(name = "skill_id")
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Integer id;
  private String name;
  
  @ManyToOne(cascade = CascadeType.ALL)
  @JoinTable(name = "employee_skill", joinColumns = @JoinColumn(referencedColumnName = "skill_id", insertable = false, updatable = false), inverseJoinColumns = @JoinColumn(referencedColumnName = "employee_id", insertable = false, updatable = false))
  private Employee employee;
  
  public Integer getId() {
      return id;
  }
  
  public void setId(Integer id) {
      this.id = id;
  }
  
  public String getName() {
      return name;
  }
  
  public void setName(String name) {
      this.name = name;
  }   
  
  
  public Employee getEmployee() {
      return employee;
  }
  
  public void setEmployee(Employee employee) {
      this.employee = employee;
  }
  </code></pre>
  
  <p>}</p>
  
  <p>When both of them was UNI-Directional, I can save employee object associate with skill.</p>
  
  <p>NOW when I tried to make it BI-Directional, I am getting sql error saying that <code>Field 'skill_id' doesn't have a default value</code></p>
  
  <p>I have no idea where did I make it wrong. Could you please point out.</p>