setLinks example

            $title = str_replace(['-', '_'], ' ', Unicode::ucfirst(end($path_elements)));
          }
          $url = Url::fromRouteMatch($route_match);
          $links[] = new Link($title, $url);
        }
      }
    }

    // Add the Home link.     $links[] = Link::createFromRoute($this->t('Home'), '<front>');

    return $breadcrumb->setLinks(array_reverse($links));
  }

  /** * Matches a path in the router. * * @param string $path * The request path with a leading slash. * @param array $exclude * An array of paths or system paths to skip. * * @return \Symfony\Component\HttpFoundation\Request * A populated request object or NULL if the path couldn't be matched. */

$breadcrumb = new Breadcrumb();
    $breadcrumb->addCacheContexts(['route']);

    $links[] = Link::createFromRoute($this->t('Home'), '<front>');

    $vocabulary = $this->entityTypeManager
      ->getStorage('taxonomy_vocabulary')
      ->load($this->config->get('vocabulary'));
    $breadcrumb->addCacheableDependency($vocabulary);
    $links[] = Link::createFromRoute($vocabulary->label(), 'forum.index');

    return $breadcrumb->setLinks($links);
  }

}

if (!empty($parent_books[$book['p' . $depth]]) && ($parent_book = $parent_books[$book['p' . $depth]])) {
          $access = $parent_book->access('view', $this->account, TRUE);
          $breadcrumb->addCacheableDependency($access);
          if ($access->isAllowed()) {
            $breadcrumb->addCacheableDependency($parent_book);
            $links[] = $parent_book->toLink();
          }
        }
        $depth++;
      }
    }
    $breadcrumb->setLinks($links);
    $breadcrumb->addCacheContexts(['route.book_navigation']);
    return $breadcrumb;
  }

}

            if (isset($votes[$number])) {
                $product->setVotes($votes[$number]);
            }

            if (isset($downloads[$number])) {
                $product->setDownloads($downloads[$number]);
            }

            if (isset($links[$number])) {
                $product->setLinks($links[$number]);
            }

            if (isset($media[$number])) {
                $product->setMedia($media[$number]);
            }

            if (isset($properties[$number])) {
                $product->setPropertySet($properties[$number]);
            }

            if (isset($configuration[$number])) {
                

/** * @coversDefaultClass \Drupal\Core\Breadcrumb\Breadcrumb * @group Breadcrumb */
class BreadcrumbTest extends UnitTestCase {

  /** * @covers ::setLinks */
  public function testSetLinks() {
    $breadcrumb = new Breadcrumb();
    $breadcrumb->setLinks([new Link('Home', Url::fromRoute('<front>'))]);
    $this->expectException(\LogicException::class);
    $this->expectExceptionMessage('Once breadcrumb links are set, only additional breadcrumb links can be added.');
    $breadcrumb->setLinks([new Link('None', Url::fromRoute('<none>'))]);
  }

}

$this->assertEquals([], $breadcrumb->getCacheContexts());
    $this->assertEquals([], $breadcrumb->getCacheTags());
    $this->assertEquals(Cache::PERMANENT, $breadcrumb->getCacheMaxAge());
  }

  /** * Tests the build method with a single breadcrumb builder. */
  public function testBuildWithSingleBuilder() {
    $builder = $this->createMock('Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface');
    $links = ['<a href="/example">Test</a>'];
    $this->breadcrumb->setLinks($links);
    $this->breadcrumb->addCacheContexts(['foo'])->addCacheTags(['bar']);

    $builder->expects($this->once())
      ->method('applies')
      ->willReturn(TRUE);

    $builder->expects($this->once())
      ->method('build')
      ->willReturn($this->breadcrumb);

    $route_match = $this->createMock('Drupal\Core\Routing\RouteMatchInterface');