Make message formatting behaviour same as previous version

src/Monolog/Handler/SlackHandler.php

@@ -191,4 +191,12 @@ class SlackHandler extends SocketHandler
 
         return $this;
     }
+
+    public function getFormatter()
+    {
+        $formatter = parent::getFormatter();
+        $this->slackRecord->setFormatter($formatter);
+
+        return $formatter;
+    }
 }

src/Monolog/Handler/SlackWebhookHandler.php

@@ -11,8 +11,8 @@
 
 namespace Monolog\Handler;
 
+use Monolog\Formatter\FormatterInterface;
 use Monolog\Logger;
-use Monolog\Formatter\LineFormatter;
 use Monolog\Handler\Slack\SlackRecord;
 
 /**
@@ -98,4 +98,20 @@ class SlackWebhookHandler extends AbstractProcessingHandler
 
         Curl\Util::execute($ch);
     }
+
+    public function setFormatter(FormatterInterface $formatter)
+    {
+        parent::setFormatter($formatter);
+        $this->slackRecord->setFormatter($formatter);
+
+        return $this;
+    }
+
+    public function getFormatter()
+    {
+        $formatter = parent::getFormatter();
+        $this->slackRecord->setFormatter($formatter);
+
+        return $formatter;
+    }
 }