title: One-To-Many Cascade Save, ERROR: null value in column "b_id" violates not-null constraint
body: <p>When I try to insert using this relationship with cascade capability. The system got error:</p>
  
  <blockquote>
    <p>ERROR: null value in column "b_id" violates not-null constraint</p>
  </blockquote>
  
  <p>A entity.</p>
  
  <pre class="lang-java prettyprint-override"><code>@Id
  @GeneratedValue(generator = "system-uuid")
  @GenericGenerator(name = "system-uuid", strategy = "uuid2")
  private String id;
  
  @ManyToOne(cascade = {CascadeType.ALL})
  @JoinColumn(name = "b_id")
  private B b;
  </code></pre>
  
  <p>B entity.</p>
  
  <pre class="lang-java prettyprint-override"><code>@Id
  @GeneratedValue(generator = "system-uuid")
  @GenericGenerator(name = "system-uuid", strategy = "uuid2")
  private String id;
  
  @OneToMany(mappedBy = "b", cascade = { CascadeType.ALL }, fetch = FetchType.EAGER)
  private List&lt;C&gt; cs;
  </code></pre>
  
  <p>C entity.</p>
  
  <pre class="lang-java prettyprint-override"><code>@GeneratedValue(generator = "system-uuid")
  @GenericGenerator(name = "system-uuid", strategy = "uuid2")
  private String id;
  
  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "b_id", nullable = false, referencedColumnName = "id")
  private B b;
  </code></pre>
  
  <p>Execute.</p>
  
  <pre class="lang-java prettyprint-override"><code>    A a = new A();
      B b = new B();
      C c = new C();
  
      List&lt;C&gt; cs = new ArrayList&lt;C&gt;();
      cs.add(c);
  
      b.setCs(cs);
      a.setB(b);
  
      aRepository.save(a);
  </code></pre>