make HEAD/GET method rewrite configurable

src/router/BaseRouter.php

@@ -14,6 +14,10 @@
 use function Facebook\AutoloadMap\Generated\is_dev;
 
 abstract class BaseRouter<+TResponder> {
+  public function __construct(
+    private RouterOptions $options = shape('head_rewrite' => true)
+  ) {}
+
   abstract protected function getRoutes(
   ): ImmMap<HttpMethod, ImmMap<string, TResponder>>;
 
@@ -33,7 +37,7 @@ final public function routeMethodAndPath(
       }
 
       if (
-        $method === HttpMethod::HEAD && $allowed === keyset[HttpMethod::GET]
+        $this->options['head_rewrite'] && $method === HttpMethod::HEAD && $allowed === keyset[HttpMethod::GET]
       ) {
         list($responder, $data) = $resolver->resolve(HttpMethod::GET, $path);
         $data = Dict\map($data, $value ==> \urldecode($value));

src/router/RouterOptions.php

@@ -0,0 +1,16 @@
+<?hh // strict
+
+/*
+ *  Copyright (c) 2015-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+namespace Facebook\HackRouter;
+
+type RouterOptions = shape(
+  'head_rewrite' => bool,
+);

tests/lib/TestRouter.php

@@ -21,6 +21,7 @@ public function __construct(
     private dict<string, T> $routes,
     private ?IResolver<T> $resolver = null,
   ) {
+    parent::__construct();
   }
 
   <<__Override>>