Classes/Console/Install/FolderStructure/ExtensionFactory.php
public function getExtensionStructure(PackageInterface $package)
    {
        $structure = [
            'name' => substr(PATH_site, 0, -1),
            'targetPermission' => $GLOBALS['TYPO3_CONF_VARS']['SYS']['folderCreateMask'],
            'children' => $this->appendStructureDefinition([], $this->createExtensionStructureDefinition([$package])),
        ];

        return new StructureFacade(new RootNode($structure));
    }
public function getExtensionStructure(PackageInterface $package)
    {
        $structure = [
            'name' => substr(PATH_site, 0, -1),
            'targetPermission' => $GLOBALS['TYPO3_CONF_VARS']['SYS']['folderCreateMask'],
            'children' => $this->appendStructureDefinition([], $this->createExtensionStructureDefinition([$package])),
        ];

        return new StructureFacade(new RootNode($structure));
    }
Creates the folder structure for one extension

@param PackageInterface $package
@return StructureFacade