Problem description
During Spring 25 commonalities a very restrictive pattern was defined for the values supported in the x-correlator header.
https://github.com/camaraproject/Commonalities/blob/r2.3/documentation/API-design-guidelines.md#9-architecture-headers

We have identified that it can be a limitation for the APPs.

• An APP may already be using correlators with a specific format that it wishes to reuse as a correlator in requests to APIs or in request to the authentication server to obtain the access tokens.

• If the APP is forced to use such a restrictive format, it would either need to change the format of its existing correlators or maintain mapping tables between its internal correlators and the correlators used to send its requests to the APIs.

Possible evolution
In order to avoid those limitations the following change is proposed:
Establish as a valid correlator any value supported by an HTTP header as defined in the RFC that standardizes the values allowed in HTTP headers:
RFC7230: https://datatracker.ietf.org/doc/html/rfc7230#section-3.2
RFC9110: https://datatracker.ietf.org/doc/html/rfc9110#section-6.3 // https://datatracker.ietf.org/doc/html/rfc9110#section-5.5

Alternative solution

Additional context