title: JPA Mapping issue one table with multiple tables
body: <p>I have a table for managing approval and I don't want add more additional columns as a reference to it</p>
  
  <p><strong>Approval.java</strong></p>
  
  <pre><code>@Entity
  @Table
  public  class Approval {
    @Id
    private int id;
    @Column
    private int doc_key; 
    @Column
    private int stage; 
    @Column
    private int status; 
    //getter and setter
  }
  </code></pre>
  
  <p>and I have tow type of documents RFQ and Contract which need approval </p>
  
  <p><strong>RFQ.java</strong></p>
  
  <pre><code>@Entity
  @Table
  public  class RFQ {
    @Id
    private int id;
  
    @Column
    private int status; 
  
    @OneToMany(mappedBy = "dockey" , fetch=FetchType.LAZY ,cascade = CascadeType.ALL)
    private List&lt;Approval&gt; approvallist; 
  
  }
  </code></pre>
  
  <p><strong>Contract.java</strong></p>
  
  <pre><code>@Entity
  @Table
  public  class Contract {
       @Id
        private int id;
  
       @Column
        private int status; 
  
        @OneToMany(mappedBy = "dockey" , fetch=FetchType.LAZY ,cascade = CascadeType.ALL)
        private List&lt;Approval&gt; approvallist; 
  
  
  }
  </code></pre>
  
  <p>as you see I am using this association mapping :</p>
  
  <pre><code>@OneToMany(mappedBy = "dockey" , fetch=FetchType.LAZY ,cascade = CascadeType.ALL)
  
  </code></pre>
  
  <p>but it is not working unless I have one of document classes RFQ or Contract
  what if I want to add another document like Porposal foe example</p>