How to use OAuth2RestTemplate?

You can find examples for writing OAuth clients here:

• https://github.com/spring-projects/spring-security-oauth

In your case you can’t just use default or base classes for everything, you have a multiple classes Implementing OAuth2ProtectedResourceDetails. The configuration depends of how you configured your OAuth service but assuming from your curl connections I would recommend:

@EnableOAuth2Client
@Configuration
class MyConfig{

    @Value("${oauth.resource:http://localhost:8082}")
    private String baseUrl;
    @Value("${oauth.authorize:http://localhost:8082/oauth/authorize}")
    private String authorizeUrl;
    @Value("${oauth.token:http://localhost:8082/oauth/token}")
    private String tokenUrl;

    @Bean
    protected OAuth2ProtectedResourceDetails resource() {
        ResourceOwnerPasswordResourceDetails resource;
        resource = new ResourceOwnerPasswordResourceDetails();

        List scopes = new ArrayList<String>(2);
        scopes.add("write");
        scopes.add("read");
        resource.setAccessTokenUri(tokenUrl);
        resource.setClientId("restapp");
        resource.setClientSecret("restapp");
        resource.setGrantType("password");
        resource.setScope(scopes);
        resource.setUsername("**USERNAME**");
        resource.setPassword("**PASSWORD**");
        return resource;
    }

    @Bean
    public OAuth2RestOperations restTemplate() {
        AccessTokenRequest atr = new DefaultAccessTokenRequest();
        return new OAuth2RestTemplate(resource(), new DefaultOAuth2ClientContext(atr));
    }
}

@Service
@SuppressWarnings("unchecked")
class MyService {

    @Autowired
    private OAuth2RestOperations restTemplate;

    public MyService() {
        restTemplate.getAccessToken();
    }
}

Do not forget about @EnableOAuth2Client on your config class, also I would suggest to try that the urls you are using are working with curl first, also try to trace it with the debugger because lot of exceptions are just consumed and never printed out due security reasons, so it gets little hard to find where the issue is. You should use logger with debug enabled set.
Good luck

I uploaded sample springboot app on github https://github.com/mariubog/oauth-client-sample
to depict your situation because I could not find any samples for your scenario .