Use void instead of null where appropriate when pipe-delimiting @return types. If a @return only contains void, remove it.

See #32444.


git-svn-id: https://develop.svn.wordpress.org/trunk@32568 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-customize-control.php

@@ -1130,7 +1130,7 @@ class WP_Customize_Header_Image_Control extends WP_Customize_Image_Control {
 	}
 
 	/**
-	 * @return string|null
+	 * @return string|void
 	 */
 	public function get_current_image_src() {
 		$src = $this->value();