buffer() {
        // Check cache and return if body has already been parsed
        if (this._body_buffer) return Promise.resolve(this._body_buffer);

        // Initialize the buffer promise if it does not exist
        this._buffer_promise = new Promise((resolve) =>
            this._body_parser_get_received_data().then((raw) => {
                // Convert the Uint8Array buffer into a Buffer
                this._body_buffer = Buffer.from(raw);

                // Resolve the buffer promise with the body buffer
                resolve(this._body_buffer);
            })
        );

        // Return the buffer promise
        return this._buffer_promise;
    }
Returns the incoming request body as a Buffer.
@returns {Promise<Buffer>}