private function initColumnTypeExtensions()
    {
        $this->columnTypeExtensions = [];

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

            $type = $extension->getExtendedType();

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