Keep PHP binary responses as strings for easier manipulation.

modules/swagger-codegen/src/main/resources/php/ObjectSerializer.mustache

@@ -242,7 +242,7 @@ class ObjectSerializer
             }
             $deserialized = $values;
         } elseif ($class === 'ByteArray') { // byte array
-            $deserialized = unpack('C*', (string)$data);
+            $deserialized = (string)$data;
         } elseif ($class === '\DateTime') {
             $deserialized = new \DateTime($data);
         } elseif (in_array($class, array({{&primitives}}))) {

modules/swagger-codegen/src/main/resources/php/api.mustache

@@ -188,7 +188,7 @@ use \{{invokerPackage}}\ObjectSerializer;
         {{#bodyParams}}// body params
         $_tempBody = null;
         if (isset(${{paramName}})) {
-            {{^isBinary}}$_tempBody = ${{paramName}};{{/isBinary}}{{#isBinary}}$_tempBody = call_user_func_array('pack', array_merge(array('C*'), ${{paramName}}));{{/isBinary}}
+            $_tempBody = ${{paramName}};
         }{{/bodyParams}}
   
         // for model (json/xml)