How to login using oauth in Springboot / Spring - spring-boot

Question

We have one authservice that is running on different machine and this it provides oauth login.
So I need to write a client to get a access token. For that I wrote following piece of code. but its not working.
String polarisOauthURL = "https://test.com/auth/oauth/token";
ClientCredentialsResourceDetails resourceDetails = new ClientCredentialsResourceDetails ();
resourceDetails.setAccessTokenUri(polarisOauthURL);
resourceDetails.setClientId("test");
resourceDetails.setClientSecret("test");
resourceDetails.setGrantType("client_credentials");
List<String> scope = new ArrayList<>();
scope.add("read");
// scope.add("write");
resourceDetails.setScope(scope);
DefaultOAuth2ClientContext clientContext = new DefaultOAuth2ClientContext();
OAuth2RestTemplate oauthRestTemplate = new OAuth2RestTemplate(resourceDetails, clientContext);
List messageConverters = new ArrayList<>();
messageConverters.add(new MappingJackson2HttpMessageConverter());
oauthRestTemplate.setMessageConverters(messageConverters);
System.out.println("access token: " + oauthRestTemplate.getAccessToken());
when the last line getAccessToken executed it thows an following error.
error="access_denied", error_description="Error requesting access token."
at org.springframework.security.oauth2.client.token.OAuth2AccessTokenSupport.retrieveToken(OAuth2AccessTokenSupport.java:145)
at org.springframework.security.oauth2.client.token.grant.client.ClientCredentialsAccessTokenProvider.obtainAccessToken(ClientCredentialsAccessTokenProvider.java:44)
at org.springframework.security.oauth2.client.token.AccessTokenProviderChain.obtainNewAccessTokenInternal(AccessTokenProviderChain.java:148)
at org.springframework.security.oauth2.client.token.AccessTokenProviderChain.obtainAccessToken(AccessTokenProviderChain.java:121)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.acquireAccessToken(OAuth2RestTemplate.java:221)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.getAccessToken(OAuth2RestTemplate.java:173)
but when I am trying to the same thing from console then its working fine.
curl --user test:test --data 'grant_type=client_credentials' https://test.com/auth/oauth/token
Could someone help me how I can achieve this think in spring.
Thanks

Answer 1

I assume, that the code does send the client id and secret inside the body of the POST Request, whereas the curl command does use HTTP basic authentication wrapping those credentials base64 encoded inside an authorization header following the rules of HTTP basic auth. To ensure this in the code you might try to add something like this:
resourceDetails.setClientAuthenticationScheme(AuthenticationScheme.header);