updateContentType() {
        // Set content-type header based on file extension
        const extension = this.filePath.toString().split('.').pop().toLowerCase();
        this.headers.set('content-type', CONTENT_TYPE_MAP[extension] ?? 'application/octet-stream');
    }
Updates the 'content-type' header property of the response based on the extension of
the file specified by the filePath property of the current object.
@returns {void}