source/php/Admin/AdminDisplayEvent.php
public function eventImage($object, $box)
    {
        ?>
        <div class="event-integration-box">
            <?php if (get_the_post_thumbnail($object->ID)): ?>
                <?php echo get_the_post_thumbnail( $object->ID, array( 266, 266), array('class' => 'featured-image')); ?>
            <?php else: ?>
                <p><?php _e('Image missing', 'event-integration') ?></p>
            <?php endif; ?>
        </div>
    <?php
    }
public function eventImage($object, $box)
    {
        ?>
        <div class="event-integration-box">
            <?php if (get_the_post_thumbnail($object->ID)): ?>
                <?php echo get_the_post_thumbnail( $object->ID, array( 266, 266), array('class' => 'featured-image')); ?>
            <?php else: ?>
                <p><?php _e('Image missing', 'event-integration') ?></p>
            <?php endif; ?>
        </div>
    <?php
    }
/*
Display event-image-box