title: Unique Value in JPA Issue
body: <p>My Entity contains <code>Long id</code> attribute and i get JSON request from user with <code>id</code> value,</p>
  <p>When i tried to save it first time, it saving, and when i tried to use same <code>id</code> in JPA save method, it is saving also. I use the below,</p>
  <pre><code>    @Id
      @GeneratedValue(strategy=GenerationType.IDENTITY)
      @Column(name = &quot;id&quot;, unique = true)
      private Long id;
  </code></pre>
  <p>and i tried with the below,</p>
  <pre><code>@Table(name = &quot;Person&quot;,
          uniqueConstraints={
                  @UniqueConstraint(columnNames = {&quot;id&quot;})})
  </code></pre>
  <p>also not working.  My request JSON as below, and if i use the same JSON for next request also saving.</p>
  <pre><code>{
    &quot;id&quot;:1,
    &quot;name&quot;:&quot;John&quot;
  }
  </code></pre>