aws/aws-sdk-php — pull request #422 by adamaveray (2014-12-04 15:13:10+00:00)
Title: Support DateTimeImmutable instances

Currently, passing a [`\DateTimeImmutable`](http://php.net/manual/en/class.datetimeimmutable.php) instance instead of a `\DateTime` will fail, as it explicitly tests for `instanceof \DateTime`. This changes it to test against [`\DateTimeInterface`](http://php.net/manual/en/class.datetimeinterface.php), of which both `\DateTime` and `\DateTimeImmutable` implement, allowing either to be provided.