Reply's content-type header value suffix stripped when charset is omitted

[JakobJingleheimer]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

3.27.4

Plugin version

No response

Node.js version

17.7.2

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

12.2

Description

In the example here, fastify strips ; version=2 (and appends ; charset=utf-8) when reply.send() is called.

Steps to Reproduce

Bad:

reply.header(
  'Content-Type',
  `application/vnd.example.com+json; version=2`,
);

reply.send({ foo: 'bar' });

fastify.log.info(reply.getHeaders());
// content-type: application/vnd.example.com+json; charset=utf-8

Good:

reply.header(
  'Content-Type',
  `application/vnd.example.com+json; version=2; charset=utf-8`,
);

reply.send({ foo: 'bar' });

fastify.log.info(reply.getHeaders());
// content-type: application/vnd.example.com+json; version=2; charset=utf-8

Expected Behavior

The existing suffix should not be stripped and ; charset=utf-8 should be appended after.

[xtx1130]

Seems like this pr #2315 has a problem, I will take a look

[JakobJingleheimer]

Wow! Thanks for the fast turnaround!