title: How to create Hidden type Field in Drupal 8 Entity
body: <p>I am using drupal 8, I have an Entity, I want to add a hidden type field in Entity Form. How I can add hidden field type? like below</p>
  
  <pre><code>&lt;form&gt;
      &lt;input type='hidden' name='my_hidden' /&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>Code Generating Form is as below:</p>
  
  <pre><code>public static function baseFieldDefinitions(EntityTypeInterface $entity_type) 
  {
     $fields = parent::baseFieldDefinitions($entity_type);
      $fields['id'] = BaseFieldDefinition::create('integer')
        -&gt;setLabel(t('ID'))
        -&gt;setDescription(t('The ID of the Timeslot entity.'))
        -&gt;setReadOnly(TRUE);
      return $fields;
  }
  </code></pre>