title: Set entity field default value using YML
body: <p>I need get default value in class file</p>
  
  <pre><code>private $example_field = 0;
  </code></pre>
  
  <p>When I use this</p>
  
  <pre><code>example_field:
      options:
          default: 0
  </code></pre>
  
  <p>I got default database value, but when I try to persist without setting "su" I got error (column 'su' cannot be null).</p>
  
  <p>Anyway,</p>
  
  <pre><code>example_field:
      default: 0
  </code></pre>
  
  <p>Does nothing.</p>