[BUG] secured aas-env container from the BaSyx Go secured example fails to start

[mm-hsh]

Describe the bug
The secured aas-env container from the BaSyx Go secured example fails to start.
The application stops during initialization with an OAuth access token retrieval error:

AccessTokenRetrievalException: Error occurred while retrieving access token
com.nimbusds.oauth2.sdk.TokenErrorResponse

This failure occurs during preconfiguration when the AAS Environment attempts to obtain a Keycloak token using the client‑credentials flow.

To Reproduce
Steps to reproduce the behavior:

1. Clone the secured example:
   https://github.com/eclipse-basyx/basyx-go-components/tree/main/examples/BaSyxSecuredExample
2. Run

docker-compose up

3. Wait for the aas-env container to start
4. The container terminates with a token retrieval exception during Spring Boot initialization

Log excerpt:

Error creating bean 'preconfigurationLoaderInitializer':
Error occurred while retrieving access token
com.nimbusds.oauth2.sdk.TokenErrorResponse
...
AuthorizedAASEnvironmentPreconfigurationLoader.configureSecurityContext
ClientCredentialAccessTokenProvider.getTokenResponse

Expected behavior
The secured AAS Environment container should:

• Successfully authenticate with Keycloak
• Retrieve an OAuth access token
• Load preconfigured AAS environments
• Start normally without crashing

BaSyx (please complete the following information):

• BaSyx Version [e.g. v1.3, v2.0]
• BaSyx SDK : Go
• AAS Version : DotAAS V3

Screenshots
If applicable, add screenshots to help explain your problem.

Used Asset Administration files (.aasx/.json/.xml)
No AAS files used.
The error happens before any AAS file is loaded.

BaSyx configuration
Using the official secured example from:
https://github.com/eclipse-basyx/basyx-go-components/tree/main/examples/BaSyxSecuredExample
Possible issues observed:

• Keycloak client ID/secret mismatch
• Incorrect token endpoint URL
• Missing realm import
• Missing compose environment variables

Additional context

• Only the secured AAS Environment container fails.
• The error originates in ClientCredentialAccessTokenProvider, indicating Keycloak authentication is not configured correctly in the example.