[Yii 2.1] - Rest actions not setting headers right

[johonunu]

What steps will reproduce the problem?

Create REST controller with model and call create action.

What's expected?

Get "created" response.

What do you get instead?

Throws error.

Additional info

{
	"name": "Exception",
	"message": "Call to a member function set() on array",
	"code": 0,
	"type": "Error",
	"file": "/home/nikola/Projects/yii2.1/vendor/yiisoft/yii2-rest/src/CreateAction.php",
	"line": 56,
	"stack-trace": [
		"#0 /home/nikola/Projects/yii2.1/vendor/yiisoft/yii2/base/Action.php(94): yii\\rest\\CreateAction->run()",
		"#1 /home/nikola/Projects/yii2.1/vendor/yiisoft/yii2/base/Controller.php(157): yii\\base\\Action->runWithParams(Array)",
		"#2 /home/nikola/Projects/yii2.1/vendor/yiisoft/yii2/base/Module.php(528): yii\\base\\Controller->runAction('create', Array)",
		"#3 /home/nikola/Projects/yii2.1/vendor/yiisoft/yii2/web/Application.php(103): yii\\base\\Module->runAction('post/create', Array)",
		"#4 /home/nikola/Projects/yii2.1/vendor/yiisoft/yii2/base/Application.php(396): yii\\web\\Application->handleRequest(Object(yii\\web\\Request))",
		"#5 /home/nikola/Projects/yii2.1/public/index.php(11): yii\\base\\Application->run()",
		"#6 {main}"
	]
}

Calling inside "CreateAction" and "OptionAction":

$response->getHeaders()->set(...

Instead of:

$response->getHeaderCollection()->set(...

Q	A
Yii version	2.1
Yii REST version
PHP version	7.2
Operating system	Arch Linux