title: JPA: constraints violation on delete
body: <p>I have three entities -</p>
  
  <pre><code>public class ApplicationEntity extends ModelEntity implements Application {
      @ManyToOne(fetch = FetchType.LAZY, optional = false, cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
      private CategoryEntity category;
  
      @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH})
      @JoinTable(
              joinColumns = {@JoinColumn(name = "APPLICATION_ID")},
              inverseJoinColumns = {@JoinColumn(name = "USER_ID")},
              uniqueConstraints = {@UniqueConstraint(columnNames = {"APPLICATION_ID", "USER_ID"})
              })
      private List&lt;UserEntity&gt; buyers = new ArrayList&lt;UserEntity&gt;();}
  
  public class CategoryEntity extends ModelEntity implements Category {
  
      @Column(nullable = false)
      private String name;
      @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
      private List&lt;ApplicationEntity&gt; applications = new ArrayList&lt;ApplicationEntity&gt;();
  }
  
      public class UserEntity extends AbstractEntity  implements User {
  }
  </code></pre>
  
  <p>When I try to delete AppliationEntity, I get a constraints violation exception. I tried to remove application entry from CategoryEntity, and then delete the ApplicationEntity. But still fails. The exception is something like --</p>
  
  <pre><code>    Caused by: java.sql.SQLException: DELETE on table 'APPLICATIONENTITY' caused a violation of foreign key constraint 'FK109DF15D362F642' for key (32779).  The statement has been rolled back.
      at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
      at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
      ... 61 more
  Caused by: ERROR 23503: DELETE on table 'APPLICATIONENTITY' caused a violation of foreign key constraint 'FK109DF15D362F642' for key (32779).  The statement has been rolled back.
  </code></pre>
  
  <p>Any suggestion is highly appreciated. Thanks in Advance.</p>