private function initTableTypeExtensions()
    {
        $this->tableTypeExtensions = [];

        foreach ($this->loadTableTypeExtensions() as $extension) {
            if (!$extension instanceof TableTypeExtensionInterface) {
                throw new UnexpectedTypeException($extension, TableTypeExtensionInterface::class);
            }

            $type = $extension->getExtendedType();

            $this->tableTypeExtensions[$type][] = $extension;
        }
    }