Developers, I need a solution to read outlook mail with springboot by client_secret. I tried with multiple process but no luck. When I debug I’ve access token but refresh token, id token size were 0. Is this causing me issue below,

Error message: Access is denied. Check credentials and try again.

GET https://graph.microsoft.com/v1.0/users/[email protected]/mailFolders/inbox/messages?%24top=5
SdkVersion : graph-java/v4.1.0

403 : Forbidden
[…]

[Some information was truncated for brevity, enable debug logging for more details]

public static void initializeGraph() throws MalformedURLException, ExecutionException, InterruptedException {    
    Set<String> SCOPE = new HashSet<>();
    SCOPE.add("https://graph.microsoft.com/.default");
    SCOPE.add("offline_access");

    IClientCredential credential = ClientCredentialFactory.createFromSecret(CLIENT_SECRET);

    ConfidentialClientApplication cca = ConfidentialClientApplication
            .builder(CLIENT_ID, credential)
            .authority(AUTHORITY)
            .build();

    IAuthenticationResult result;
    ITokenCache tokenCache = cca.tokenCache();

    try {
        SilentParameters silentParameters = SilentParameters
                .builder(SCOPE)
                .build();

        // Try to acquire token silently
        result = cca.acquireTokenSilently(silentParameters).get();
        System.out.println(result);

    } catch (Exception ex) {
        if (ex.getCause() instanceof MsalException) {
            ClientCredentialParameters parameters = ClientCredentialParameters
                    .builder(SCOPE)
                    .build();

            // Try to acquire a token
            IAuthenticationResult accessToken = cca.acquireToken(parameters).get();

            System.out.println("Token retrieved from accessToken: " + accessToken.accessToken());
            System.out.println("Token retrieved from idToken: " + accessToken.idToken());
            System.out.println("Token retrieved from tenantProfile: " + accessToken.tenantProfile());
            System.out.println("Token retrieved from expiresOnDate: " + accessToken.expiresOnDate());

            TokenCredential tokenCredential = new TokenCredential() {
                @Override
                public Mono<com.azure.core.credential.AccessToken> getToken(TokenRequestContext tokenRequestContext) {
                    String accessToken = accessToken.accessToken();
                    Instant instant = accessToken.expiresOnDate().toInstant();
                    com.azure.core.credential.AccessToken azureToken = new
                            com.azure.core.credential.AccessToken(accessToken,
                            instant.atOffset(ZoneId.systemDefault().getRules().getOffset(instant)));
                    return Mono.just(azureToken);
                }
            };

            IAuthenticationProvider authProvider = new TokenCredentialAuthProvider(tokenCredential);

            userClient = GraphServiceClient
                    .builder()
                    .authenticationProvider(authProvider)
                    .buildClient();
        } else {
            throw ex;
        }
    }
}

public static MessageCollectionPage getInbox() throws Exception { 
    initializeGraphForAppOnlyAuth(); 
    System.out.println(userClient); 
    if (userClient == null) {
        throw new Exception("Graph has not been initialized for user auth");
    }      
  
    return userClient.users("[email protected]")
            .mailFolders("inbox")
            .messages()
            .buildRequest()
            .top(5)
            .get();
}


public static MessageCollectionPage getInbox() throws Exception { 
initializeGraphForAppOnlyAuth(); 
System.out.println(userClient); 
if (userClient == null) {
throw new Exception("Graph has not been initialized for user auth");
 }      
  
return userClient.users("[email protected]")
                .mailFolders("inbox")
                .messages()
                .buildRequest()
                .top(5)
                .get();
}