[BUG] : AsyncAPI document is double-stringified in generated ZIP output

Start in src/domains/services/archiver.service.ts at appendAsyncAPIDocument, then reproduce the issue with test-archiver.ts using npx ts-node test-archiver.ts. Done means the generated ZIP's asyncapi.yml preserves the supplied YAML document as valid YAML rather than a quoted, escaped string.

Describe the bug.

In src/domains/services/archiver.service.ts, the method appendAsyncAPIDocument always applies:

asyncapi = JSON.stringify(asyncapi);

even when asyncapi is already a YAML or JSON string.

Because of this:

• The original document is converted into a JSON string literal.
• Newlines are escaped (\n) and the entire content is wrapped in quotes.
• The archived asyncapi.yml therefore contains a serialized string instead of a valid AsyncAPI document.

Expected behavior

For the test file mentioned in How to Reproduce section
The file should contain valid YAML:

asyncapi: 2.6.0
info:
  title: Example
  version: 1.0.0

Proposed fix
We can update the method to stringify only when the input is an object:

public appendAsyncAPIDocument(
  archive: Archiver,
  asyncapi: string | object,
  fileName = 'asyncapi',
) {
  const content =
    typeof asyncapi === 'string'
      ? asyncapi
      : JSON.stringify(asyncapi, null, 2);

  const language = retrieveLangauge(content);
  const extension = language === 'yaml' ? 'yml' : 'json';

  archive.append(content, { name: `${fileName}.${extension}` });
}

Screenshots

How to Reproduce

1. Create a test file named test-archiver.ts. Inside the test, pass an AsyncAPI document as a string:

import * as fs from 'fs';
import archiver from 'archiver';
import { ArchiverService } from './src/domains/services/archiver.service';

async function run() {
  const output = fs.createWriteStream('test.zip');
  const archive = archiver('zip');

  archive.pipe(output);

  const service = new ArchiverService();

  const asyncapiString =
    "asyncapi: 2.6.0\ninfo:\n  title: Example\n  version: 1.0.0";

  service.appendAsyncAPIDocument(archive, asyncapiString);

  await archive.finalize();

  console.log('ZIP created');
}

run();

2. Run the test script from the project root:

npx ts-node test-archiver.ts

3. Allow the archiver service to generate the ZIP archive.
4. Open the generated ZIP file.
5. Open asyncapi.yml inside the archive.

🖥️ Device Information [optional]

• Operating System (OS): Windows 10
• Generator version : 3.0.1

👀 Have you checked for similar open issues?

• I checked and didn't find similar issue

🏢 Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

Are you willing to work on this issue ?

Yes I am willing to submit a PR!