core-bundle/src/Resources/contao/elements/ContentGallery.php
public function generate()
	{
		// Use the home directory of the current user as file source
		if ($this->useHomeDir && FE_USER_LOGGED_IN)
		{
			$this->import(FrontendUser::class, 'User');

			if ($this->User->assignDir && $this->User->homeDir)
			{
				$this->multiSRC = array($this->User->homeDir);
			}
		}
		else
		{
			$this->multiSRC = StringUtil::deserialize($this->multiSRC);
		}

		// Return if there are no files
		if (empty($this->multiSRC) || !\is_array($this->multiSRC))
		{
			return '';
		}

		// Get the file entries from the database
		$this->objFiles = FilesModel::findMultipleByUuids($this->multiSRC);

		if ($this->objFiles === null)
		{
			return '';
		}

		return parent::generate();
	}
public function generate()
	{
		// Use the home directory of the current user as file source
		if ($this->useHomeDir && FE_USER_LOGGED_IN)
		{
			$this->import(FrontendUser::class, 'User');

			if ($this->User->assignDir && $this->User->homeDir)
			{
				$this->multiSRC = array($this->User->homeDir);
			}
		}
		else
		{
			$this->multiSRC = StringUtil::deserialize($this->multiSRC);
		}

		// Return if there are no files
		if (empty($this->multiSRC) || !\is_array($this->multiSRC))
		{
			return '';
		}

		// Get the file entries from the database
		$this->objFiles = FilesModel::findMultipleByUuids($this->multiSRC);

		if ($this->objFiles === null)
		{
			return '';
		}

		return parent::generate();
	}
Return if there are no files

@return string