core-bundle/src/Resources/contao/classes/Backend.php
public static function getSystemMessages()
	{
		$strMessages = '';

		// HOOK: add custom messages
		if (isset($GLOBALS['TL_HOOKS']['getSystemMessages']) && \is_array($GLOBALS['TL_HOOKS']['getSystemMessages']))
		{
			$arrMessages = array();

			foreach ($GLOBALS['TL_HOOKS']['getSystemMessages'] as $callback)
			{
				$strBuffer = System::importStatic($callback[0])->{$callback[1]}();

				if ($strBuffer != '')
				{
					$arrMessages[] = $strBuffer;
				}
			}

			if (!empty($arrMessages))
			{
				$strMessages .= implode("\n", $arrMessages);
			}
		}

		return $strMessages;
	}
public static function getSystemMessages()
	{
		$strMessages = '';

		// HOOK: add custom messages
		if (isset($GLOBALS['TL_HOOKS']['getSystemMessages']) && \is_array($GLOBALS['TL_HOOKS']['getSystemMessages']))
		{
			$arrMessages = array();

			foreach ($GLOBALS['TL_HOOKS']['getSystemMessages'] as $callback)
			{
				$strBuffer = System::importStatic($callback[0])->{$callback[1]}();

				if ($strBuffer != '')
				{
					$arrMessages[] = $strBuffer;
				}
			}

			if (!empty($arrMessages))
			{
				$strMessages .= implode("\n", $arrMessages);
			}
		}

		return $strMessages;
	}
Return the system messages as HTML

@return string The messages HTML markup