src/Message/Message.php
protected function setDefaultOptions(OptionsResolver $resolver)
    {
        parent::setDefaultOptions($resolver);

        $resolver->setTypesAllowed([
            'attachments' => '\Crummy\Phlack\Message\Collection\AttachmentCollection',
        ]);

        $resolver->setNormalizers([
            'icon_emoji' => function (Options $options, $value) {
                return empty($value) ? $value : sprintf(':%s:', trim($value, ':'));
            },
        ]);
    }
protected function setDefaultOptions(OptionsResolver $resolver)
    {
        parent::setDefaultOptions($resolver);

        $resolver->setTypesAllowed([
            'attachments' => '\Crummy\Phlack\Message\Collection\AttachmentCollection',
        ]);

        $resolver->setNormalizers([
            'icon_emoji' => function (Options $options, $value) {
                return empty($value) ? $value : sprintf(':%s:', trim($value, ':'));
            },
        ]);
    }
{@inheritdoc}