------------------------------------------------------------------
== POST /oauth2/token   grant_type=client_credentials
------------------------------------------------------------------
$ curl -su demo-service:service-secret -d grant_type=client_credentials \
       -d scope=orders.read http://localhost:9000/oauth2/token
{
    "access_token": "DE0Ps3Jo6f6IdZ1Jd6bqBg_HnYTatIanVFutxdNihyAkHjlgMHWElxo4TGiWI9oNkxgdOAZZu6vgW9BXZrd_KkYVkKrV238fmHUCD9Xpz0_U3k55Brs9fXcMwxxTKGWa",
    "scope": "orders.read",
    "token_type": "Bearer",
    "expires_in": 599
}

------------------------------------------------------------------
== Not a JWT
------------------------------------------------------------------
The access token is an opaque reference: DE0Ps3Jo6f6IdZ1Jd6bqBg_HnYTatIanVFutxdNihyAkHjlgMHWElxo4TGiWI9oNkxgdOAZZu6vgW9BXZrd_KkYVkKrV238fmHUCD9Xpz0_U3k55Brs9fXcMwxxTKGWa
Length 128. It carries no claims; the resource server must introspect it.

------------------------------------------------------------------
== POST /oauth2/introspect
------------------------------------------------------------------
{
    "active": true,
    "sub": "demo-service",
    "aud": [
        "demo-service"
    ],
    "nbf": 1787538776,
    "scope": "orders.read",
    "iss": "http://localhost:9000",
    "exp": 1787539376,
    "iat": 1787538776,
    "jti": "9d96a819-4f1e-4efb-8816-4523bb6def61",
    "client_id": "demo-service",
    "token_type": "Bearer"
}

------------------------------------------------------------------
== Wrong secret
------------------------------------------------------------------
$ curl -si -u demo-service:WRONG -d grant_type=client_credentials http://localhost:9000/oauth2/token
HTTP/1.1 401
{"error":"invalid_client"}
------------------------------------------------------------------
== A grant the client is not registered for
------------------------------------------------------------------
$ curl -si -u demo-service:service-secret -d grant_type=authorization_code -d code=x http://localhost:9000/oauth2/token
HTTP/1.1 400
{"error":"invalid_grant"}
------------------------------------------------------------------
== A scope the client is not registered for
------------------------------------------------------------------
$ curl -s -u demo-service:service-secret -d grant_type=client_credentials -d scope=orders.write http://localhost:9000/oauth2/token
{"error":"invalid_scope"}

------------------------------------------------------------------
== Calling the resource server with the token
------------------------------------------------------------------
GET /public -> 401
  WWW-Authenticate: Bearer error="invalid_token", error_description="An error occurred while attempting to decode the Jwt: Malformed token", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1", resource_metadata="http://localhost:8090/.well-known/oauth-protected-resource"

GET /api/orders -> 401
  WWW-Authenticate: Bearer error="invalid_token", error_description="An error occurred while attempting to decode the Jwt: Malformed token", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1", resource_metadata="http://localhost:8090/.well-known/oauth-protected-resource"

GET /api/admin -> 401
  WWW-Authenticate: Bearer error="invalid_token", error_description="An error occurred while attempting to decode the Jwt: Malformed token", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1", resource_metadata="http://localhost:8090/.well-known/oauth-protected-resource"