Adding separate method to fetch extensions.

Author: fubhy

src/Plugin/GraphQL/Schema/SdlSchemaPluginBase.php

@@ -113,7 +113,7 @@ public function __construct(
    * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
    */
   public function getSchema(ResolverRegistryInterface $registry) {
-    $extensions = $this->extensionManager->getExtensions($this->getPluginId());
+    $extensions = $this->getExtensions();
     $resolver = [$registry, 'resolveType'];
     $document = $this->getSchemaDocument($extensions);
     $schema = BuildSchema::build($document, function ($config, TypeDefinitionNode $type) use ($resolver) {
@@ -135,6 +135,13 @@ public function getSchema(ResolverRegistryInterface $registry) {
     return SchemaExtender::extend($schema, $this->getExtensionDocument($extensions));
   }
 
+  /**
+   * @return \Drupal\graphql\Plugin\SchemaExtensionPluginInterface[]
+   */
+  protected function getExtensions() {
+    return $this->extensionManager->getExtensions($this->getPluginId());
+  }
+
   /**
    * Retrieves the parsed AST of the schema definition.
    *