title: @OrderColumn causes null elements in collection after update
body: <p>I'm trying to maintain order of bi-directionally mapped collection. Mapping like:</p>
  <pre><code>@Entity
  public class Plate {
      ...
      @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = &quot;plate&quot;)
      @OrderColumn
      private List&lt;W&gt; wells = new ArrayList&lt;&gt;();
  
      ...
  }
  </code></pre>
  <p>And reverse mapping:</p>
  <pre><code>@Entity
  public class Well {
      ...
      @ManyToOne(fetch = FetchType.LAZY)
      @JoinColumn(name = &quot;plate_id&quot;)
      private Plate plate;
  }
  </code></pre>
  <p>The firs time I save the <code>Plate</code> entity the collection of 96 <code>Well</code>s everything is saved correctly and the <code>order</code> column is populated in database starting at 0 going up to 95. All good.</p>
  <p>After subsequent update to <code>Plate</code> entity though (without really changing any of the <code>Well</code>) and save I see bunch of updates to the <code>order</code> column in DB resulting in the 96 elements be indexed starting from 97 going to 193.</p>
  <p>As a result after next load of such collection the <code>List</code> contains 97 <code>null</code> elements followed by the expected 96 real elements (the list now has 193 elements in total).</p>
  <p>The catch is the <em>bug</em> (?) doesn't reveal itself when you are debugging through it as probably some lazy collection gets loaded during the debugging so it is extremely difficult to tell what is the root cause.</p>
  <p>I understand this is <em>probably</em> driven somehow by <code>AbstractCollectionPersister</code> and its <code>baseIndex</code> property but can't figure out wha may lead Hibernate into reindexing collection and starting from 97 instead of 0.</p>
  <p>** Edit: ** Env
  Hibernate 5.4.18.Final
  Spring boot 2.2.9</p>