.../src/EventSubscriber/ResourceResponseSubscriber.php    | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/core/modules/rest/src/EventSubscriber/ResourceResponseSubscriber.php b/core/modules/rest/src/EventSubscriber/ResourceResponseSubscriber.php
index 338b233..ef33817 100644
--- a/core/modules/rest/src/EventSubscriber/ResourceResponseSubscriber.php
+++ b/core/modules/rest/src/EventSubscriber/ResourceResponseSubscriber.php
@@ -102,26 +102,27 @@ public function getResponseFormat(RouteMatchInterface $route_match, Request $req
     $content_type_format = $request->getContentType();
 
     // If an acceptable response format is requested, then use that. Otherwise,
-    // including  and particularly when the client forgot to specify a response
+    // including and particularly when the client forgot to specify a response
     // format, then use heuristics to select the format that is most likely
     // expected.
-    if (in_array($requested_format, $acceptable_response_formats)) {
+    if (in_array($requested_format, $acceptable_response_formats, TRUE)) {
       return $requested_format;
     }
+
     // If a request body is present, then use the format corresponding to the
     // request body's Content-Type for the response, if it's an acceptable
     // format for the request.
-    elseif (!empty($request->getContent()) && in_array($content_type_format, $acceptable_request_formats)) {
+    if (!empty($request->getContent()) && in_array($content_type_format, $acceptable_request_formats, TRUE)) {
       return $content_type_format;
     }
+
     // Otherwise, use the first acceptable format.
-    elseif (!empty($acceptable_formats)) {
+    if (!empty($acceptable_formats)) {
       return $acceptable_formats[0];
     }
+
     // Sometimes, there are no acceptable formats, e.g. DELETE routes.
-    else {
-      return NULL;
-    }
+    return NULL;
   }
 
   /**