hero-title-block.php

<?php

namespace Drupal\my_module\Plugin\Block;

use Drupal\Core\Block\BlockBase;

/**
 * Provides a 'HomeHeader' block.
 *
 * @Block(
 *  id = "home_header",
 *  admin_label = @Translation("Home Header"),
 *  context = {
 *    "node" = @ContextDefinition("entity:node", label = @Translation("Node"))
 *  }
 * )
 */
class HomeHeader extends BlockBase {

  /**
   * {@inheritdoc}
   */
  public function build() {
    $node = $this->getContextValue('node');

    $build = [];

    $build['title'] = [
      '#title' => $node->title->value,
      '#theme' => 'page_title',
    ];

    if ($node->hasField('field_hero_description') && !$node->get('field_hero_description')->isEmpty()) {
      $build['description'] = $node->field_hero_description->view('teaser');
    }

    if ($node->hasField('field_hero_link') && !$node->get('field_hero_link')->isEmpty()) {
      $build['link'] = $node->field_hero_link->view('teaser');
    }

    return $build;
  }
}