add missing typehints and return types;

src/DocBlock/DescriptionFactory.php

@@ -61,7 +61,7 @@ class DescriptionFactory
      *
      * @return string[] A series of tokens of which the description text is composed.
      */
-    private function lex(string $contents)
+    private function lex(string $contents): array
     {
         $contents = $this->removeSuperfluousStartingWhitespace($contents);