Acquiring access token using MSAL for JAVA

Question

Hello,

we used ADAL 4J for a couple of years now and it worked fine. Now we're migrating to MSAL. Our flow is:

1. Acquire Token using Username & Password via PublicClientApplication
2. Use the token to get User related information via Graph API and I can't get it to work because it always throws the following error: java.lang.ClassCastException: java.util.Collections$SingletonList (loaded by <bootstrap>) cannot be cast to java.lang.String (loaded by <bootstrap>)
   at com.nimbusds.oauth2.sdk.util.URLUtils.serializeParameters(URLUtils.java:105)
   at com.microsoft.aad.msal4j.TokenRequestExecutor.createOauthHttpRequest(TokenRequestExecutor.java:57)
   at com.microsoft.aad.msal4j.TokenRequestExecutor.executeTokenRequest(TokenRequestExecutor.java:35)
   at com.microsoft.aad.msal4j.AbstractClientApplicationBase.acquireTokenCommon(AbstractClientApplicationBase.java:128)
   at com.microsoft.aad.msal4j.AcquireTokenByAuthorizationGrantSupplier.execute(AcquireTokenByAuthorizationGrantSupplier.java:63)
   at com.microsoft.aad.msal4j.AuthenticationResultSupplier.get(AuthenticationResultSupplier.java:69)
   at com.microsoft.aad.msal4j.AuthenticationResultSupplier.get(AuthenticationResultSupplier.java:18)
   at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1604)
   at java.lang.Thread.run(Thread.java:838)

That happens when IAuthenticationResult.get() is called. This is the code snipped which is used to aquire the token:

 private static IAuthenticationResult getAccessTokenFromUserCredentials(String username, String password) throws Exception {  
 IAuthenticationResult result;  

 UserNamePasswordParameters parameters = UserNamePasswordParameters.builder(Collections.singleton("User.Read"), username, password.toCharArray()).build();  

 PublicClientApplication application = PublicClientApplication.builder(clientId).build();  

 result = application.acquireToken(parameters).get();  

 if (result == null) {  
 throw new ServiceUnavailableException("authentication result was null");  
 }  

 return result;  
 }  

Is there anything obvious I am missing?

EDIT:
updated code snipped based on github example:

            try {  
                SilentParameters silentParameters =  
                        SilentParameters  
                                .builder(Collections.singleton("User.Read"))  
                                .account(account)  
                                .build();  
                // Try to acquire token silently. This will fail on the first acquireTokenUsernamePassword() call  
                // because the token cache does not have any data for the user you are trying to acquire a token for  
                result = pca.acquireTokenSilently(silentParameters).join();  
                LOGGER.debug("AzureAPI | AuthenticationService | getAccessTokenFromUserCredentials | acquireTokenSilently call succeeded");  
            } catch (Exception ex) {  
                if (ex.getCause() instanceof MsalException) {  
                    System.out.println("==acquireTokenSilently call failed: " + ex.getCause());  
                    UserNamePasswordParameters parameters =  
                            UserNamePasswordParameters  
                                    .builder(Collections.singleton("User.Read"), username, password.toCharArray())  
                                    .build();  
                    // Try to acquire a token via username/password. If successful, you should see  
                    // the token and account information printed out to console  
                    result = pca.acquireToken(parameters).join();  
                    LOGGER.debug("AzureAPI | AuthenticationService | getAccessTokenFromUserCredentials | username/password flow succeeded");  
                } else {  
                    // Handle other exceptions accordingly  
                    throw ex;  
                }  
            }  
            return result;