How to add a custom block in sonata

block.html.twig

{% extends 'SonataBlockBundle:Block:block_base.html.twig' %}

{% block block %}
<h2>{{ settings.title }}</h2>

<div class="sonata-feeds-container">
    {% for meeting in meetings %}
    <div>
        <div>{{ meeting.date }}, {{ meeting.time }}</div>
        <div>{{ meeting.location }}</div>
    </div>
    {% else %}
    No upcoming meetings scheduled.
    {% endfor %}
</div>
{% endblock %}

config_sonata.yml

sonata_admin:
  dashboard:
    blocks:
      - { position: right, type: my.block.service.meetings, settings: { title: Meetings } }

MeetingBlock.php

<?php
namespace My\Bundle\BlockBundle\Block;

use Symfony\Component\HttpFoundation\Response;

use Sonata\BlockBundle\Model\BlockInterface;
use Sonata\BlockBundle\Block\BaseBlockService;

use Sonata\AdminBundle\Form\FormMapper;
use Sonata\AdminBundle\Validator\ErrorElement;

class MeetingBlock extends BaseBlockService
{

    function getDefaultSettings()
    {
        return array(
            'title'   => 'My Title'
        );
    }

    /**
     * @param FormMapper     $form
     * @param BlockInterface $block
     *
     * @return void
     */
    function buildEditForm(FormMapper $form, BlockInterface $block)
    {
        $form->add('settings', 'sonata_type_immutable_array', array(
            'keys' => array(
                array('title', 'text', array('required' => false)),
            )
        ));
    }

    /**
     * @param BlockInterface $block
     * @param null|Response  $response
     *
     * @return Response
     */
    function execute(BlockInterface $block, Response $response = null)
    {
        $settings = array_merge($this->getDefaultSettings(), $block->getSettings());

        $meetings = array();

        return $this->renderResponse('MyBlockBundle:Block:block.html.twig', array(
            'settings'  => $settings,
            'meetings' => $meetings,
        ), $response);
    }

    /**
     * @param ErrorElement   $errorElement
     * @param BlockInterface $block
     *
     * @return void
     */
    function validateBlock(ErrorElement $errorElement, BlockInterface $block)
    {
        $errorElement
            ->with('settings.title')
                ->assertNotNull(array())
                ->assertNotBlank()
                ->assertMaxLength(array('limit' => 50))
            ->end();
    }
}

services.yml

services:
  my.block.service.meetings:
    class: My\Bundle\BlockBundle\Block\MeetingBlock
    tags:
      - { name: sonata.block }
    arguments: ['nameofblock?', @templating ]