--- /dev/null
+<?php
+
+namespace Drupal\libraries\ExternalLibrary\Utility;
+
+/**
+ * Provides an interface for classes giving access to a library ID.
+ */
+interface LibraryAccessorIdInterface {
+
+ /**
+ * Returns the ID of the library.
+ *
+ * @return string
+ * The library ID.
+ */
+ public function getLibraryId();
+
+}