How to Override Outbound OAuth and Propagate Incoming Authorization Token in AWS Bedrock AgentCore Gateway by Interceptor Lambda?

• I’m trying to propagate an access token from the incoming request through the gateway to the target service.
• Currently, I have configured the outbound auth as the OAuth client and I want to override the token generated from this authorizer by the token incoming in the gateway request through the interceptor.
• I have written the following request interceptor, but when the agent invoked the gateway the token didn't propagate to the target and the outbound OAuth token is being used.
• Is there a configuration step I’m missing that prevents an interceptor from overriding outbound OAuth headers? Or is outbound OAuth always applied after the interceptor runs?

def lambda_handler(event, context):
    mcp_data = event.get('mcp', {})
    gateway_request = mcp_data.get('gatewayRequest', {})
    headers = gateway_request.get('headers', {})
    credentials = headers.get('authorization', '') or headers.get('Authorization', '')

    return {
        "interceptorOutputVersion": "1.0",
        "mcp": {
            "transformedGatewayRequest": {
                "headers": {
                    "Authorization": credentials,
                },
                "body": event['mcp']['gatewayRequest']['body']
            }
        }
    }

• References: https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/gateway-headers.html#gateway-headers-interceptor-propagation