When using Forge Remote with a Spring Boot backend in Confluence, calling asUser() for an authenticated guest user (a real Atlassian account that is unlicensed in Confluence) fails with:

•  CQL: 403 Forbidden — "Current user not permitted to use Confluence"
•  REST v2: 404 Not Found
This occurs even when the app manifest correctly declares unlicensedAccess for the affected modules:

unlicensedAccess:
  - unlicensed
  - anonymous
Steps to Reproduce

 1.  Create a Forge app with a Spring Boot remote backend using the Forge Java SDK.
 2.  Declare unlicensedAccess: [unlicensed, anonymous] on the relevant Confluence module in manifest.yml.
 3.  Ensure a guest user has been granted access via global permissions and the Collaborator role.
 4.  Have the guest user load the app and trigger a backend call using asUser():

atlassianForgeRestClients.asUser().requestConfluence()
    .getForEntity("/api/v2/spaces/{id}?include-operations=true", Object.class);
 5.  Observe the 403/404 error response.
Expected Behavior
Guest users (authenticated, unlicensed) should be able to make asUser() calls in Forge Remote, consistent with the behavior available in Atlassian Connect, where user-initiated actions preserved user identity and authorization context.