Issue #3477441 by tr: Parameter typing in PlaceholderResolver service

src/PlaceholderResolver.php

 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\typed_data;
 
 use Drupal\Component\Render\HtmlEscapedText;
@@ -45,7 +47,7 @@ class PlaceholderResolver implements PlaceholderResolverInterface {
   /**
    * {@inheritdoc}
    */
-  public function resolvePlaceholders(string $text, array $data = [], BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): array {
+  public function resolvePlaceholders(string $text, array $data = [], ?BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): array {
     $options += [
       'langcode' => NULL,
       'clear' => FALSE,
@@ -163,7 +165,7 @@ class PlaceholderResolver implements PlaceholderResolverInterface {
   /**
    * {@inheritdoc}
    */
-  public function replacePlaceHolders(string $text, array $data = [], BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): string {
+  public function replacePlaceHolders(string $text, array $data = [], ?BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): string {
     $replacements = $this->resolvePlaceholders($text, $data, $bubbleable_metadata, $options);
 
     $placeholders = array_keys($replacements);

src/PlaceholderResolverInterface.php

@@ -45,7 +45,7 @@ interface PlaceholderResolverInterface {
    *   An array of replacement values for the placeholders contained in the
    *   text, keyed by placeholder.
    */
-  public function resolvePlaceholders(string $text, array $data = [], BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): array;
+  public function resolvePlaceholders(string $text, array $data = [], ?BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): array;
 
   /**
    * Replaces the placeholders in the given text.
@@ -87,7 +87,7 @@ interface PlaceholderResolverInterface {
    *   otherwise for example the result can be put into #markup, in which case
    *   it would be sanitized by Xss::filterAdmin().
    */
-  public function replacePlaceHolders(string $text, array $data = [], BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): string;
+  public function replacePlaceHolders(string $text, array $data = [], ?BubbleableMetadata $bubbleable_metadata = NULL, array $options = []): string;
 
   /**
    * Builds a list of all placeholder tokens that appear in the text.

src/PlaceholderResolverTrait.php

 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\typed_data;
 
 /**