Add nullable type hints to setters and Since ctor

Add explicit nullable type declarations for optional parameters to improve type safety: Argument::set_param_tag(?Param), Hook::set_doc_comment(?\PhpParser\Comment\Doc), Hook::set_changelog(?Changelog), and Since::__construct(..., ?string $description, ?PhpDocSince $tag). No runtime behavior changes—just stronger typing.

Author: remcotolsma

src/Argument.php

@@ -80,7 +80,7 @@ public function get_param_tag() {
 	 *
 	 * @param Param|null $param_tag Param tag.
 	 */
-	public function set_param_tag( Param $param_tag = null ) {
+	public function set_param_tag( ?Param $param_tag = null ) {
 		$this->param_tag = $param_tag;
 	}
 

src/Hook.php

@@ -130,7 +130,7 @@ public function get_doc_comment() {
 	 *
 	 * @param \PhpParser\Comment\Doc|null $doc_comment Doc comment.
 	 */
-	public function set_doc_comment( \PhpParser\Comment\Doc $doc_comment = null ) {
+	public function set_doc_comment( ?\PhpParser\Comment\Doc $doc_comment = null ) {
 		$this->doc_comment = $doc_comment;
 	}
 
@@ -286,7 +286,7 @@ public function get_changelog() {
 	 *
 	 * @param Changelog|null $changelog Changelog.
 	 */
-	public function set_changelog( Changelog $changelog = null ) {
+	public function set_changelog( ?Changelog $changelog = null ) {
 		$this->changelog = $changelog;
 	}
 

src/Since.php

@@ -48,7 +48,7 @@ class Since {
 	 * @param string|null      $description Description.
 	 * @param PhpDocSince|null $tag         Tag.
 	 */
-	public function __construct( $version, $description = null, $tag = null ) {
+	public function __construct( $version, ?string $description = null, ?PhpDocSince $tag = null ) {
 		$this->version     = $version;
 		$this->description = $description;
 		$this->tag         = $tag;