[Next.js+ApiGateway+lambda+cognito]Next.jsのでのCognito認証トークン取得,lambdaでの認証情報取得

import { fetchAuthSession } from 'aws-amplify/auth';

//省略
  const fetchAccessToken = async () => {
    
    const session = await fetchAuthSession();
    const token = session?.tokens?.idToken?.toString();
    if (token) {
        setAccessToken(token);
    }
  };

        const response = await fetch(target_url, {
          method: 'POST',
          headers: {
            'Content-Type': 'application/json',
            "Authorization": access_token
          },
          body: JSON.stringify(obj),
        });

    const auth_user = event.requestContext.authorizer;
    const auth_user_id:string = auth_user!.claims.sub ?? null;