public function getModelInstance($fileType, $parentType)
    {
        if (! isset($this->supportedFileModels[$this->getFileTypeIdentifier($fileType, $parentType)])) {
            throw new FileException(
                sprintf("Unsupported file type '%s' for parent type '%s'", $fileType, $parentType)
            );
        }

        $className = $this->supportedFileModels[$this->getFileTypeIdentifier($fileType, $parentType)];

        $instance = new $className;

        if (! $instance instanceof FileModelInterface) {
            throw new FileException(
                sprintf(
                    "Wrong class type for file type '%s', parent type '%s'. Class '%s' should implements FileModelInterface",
                    $fileType,
                    $parentType,
                    $className
                )
            );
        }

        return $instance;
    }