core-bundle/src/Resources/contao/classes/Versions.php
protected function getUsername()
	{
		if ($this->strUsername !== null)
		{
			return $this->strUsername;
		}

		$this->import(BackendUser::class, 'User');

		return $this->User->username;
	}
protected function getUsername()
	{
		if ($this->strUsername !== null)
		{
			return $this->strUsername;
		}

		$this->import(BackendUser::class, 'User');

		return $this->User->username;
	}
Return the username

@return string