Function setupTLSClientAuth

setupTLSClientAuth(
    fetchOptions: Object,
    keyFilename: string,
    certFilename: string,
    rejectUnauthorized?: boolean,
): Promise<void>
Modify fetch options for a request authenticated with a client-side TLS certificate.
Parameters
- fetchOptions: Object
  The fetch request option object to modify. (init parameter in [[fetch]] above)
- keyFilename: string
  Name of the private key file in PEM format (e.g. beginning with -----BEGIN RSA PRIVATE KEY-----)
- certFilename: string
  Name of the certificate file in PEM format (beginning with -----BEGIN CERTIFICATE-----)
- rejectUnauthorized: boolean = false
  to validate the server's certificate, false (=default) to accept invalid certificates as well.
Returns Promise<void>
Example
```
const init = {method: 'POST', body: '{"something": "secret"}'};
await setupTLSClientAuth(init, 'key.pem', 'cert.crt');
const response = await fetch(config, 'https://protected.example.org/', init);
assert.equal(response.status, 200); // 401 = invalid certificate
```
- Defined in net_utils.js:194