Caching of the access token for oidc client credential flow

[botsteve]

Helidon Version: Mp 4.2.4

Enhancement Description

In the current implementation, a new access token is fetched for every outgoing request to the protected API. This enhancement introduces a caching mechanism to reuse the access token across multiple requests, provided it is still valid .If the cached token is expired or missing, a new token will be fetched and cached.

Benefits:

• Reduces the number of calls to the OAuth token endpoint.
• Improves performance by avoiding unnecessary latency.