OAuth2.0 クライアントのサンプル実装

Resource owner password credentials grant
のクライアントサンプル実装について。Java での実装例が以下に解説されていました。
http://www.ibm.com/developerworks/library/se-oauthjavapt1/

import java.util.Properties;

public class OAuth2Client {



    public static void main(String[] args) {

        Properties config = OAuthUtils.getClientConfigProps(OAuthConstants.CONFIG_FILE_PATH);
        String resourceServerUrl = config.getProperty(OAuthConstants.RESOURCE_SERVER_URL);
        String username = config.getProperty(OAuthConstants.USERNAME);
        String password = config.getProperty(OAuthConstants.PASSWORD);
        String grantType = config.getProperty(OAuthConstants.GRANT_TYPE);
        String authenticationServerUrl = config
                .getProperty(OAuthConstants.AUTHENTICATION_SERVER_URL);

        if (!OAuthUtils.isValid(username) || !OAuthUtils.isValid(password)
                || !OAuthUtils.isValid(authenticationServerUrl)
                || !OAuthUtils.isValid(grantType)) {
            System.out
                    .println("Please provide valid values for username, password, authentication server url and grant type");
            System.exit(0);
        }
        if (!OAuthUtils.isValid(resourceServerUrl)) {
            // Resource server url is not valid. Only retrieve the access token
            System.out.println("Retrieving Access Token");
            OAuth2Details oauthDetails = OAuthUtils.createOAuthDetails(config);
            String accessToken = OAuthUtils.getAccessToken(oauthDetails);
            if(OAuthUtils.isValid(accessToken)){
            System.out
                    .println("Successfully retrieved Access token for Password Grant: "
                            + accessToken);
            }
        } else {
            // Response from the resource server must be in Json or Urlencoded or xml
            System.out.println("Resource endpoint url: " + resourceServerUrl);
            System.out.println("Attempting to retrieve protected resource");
            OAuthUtils.getProtectedResource(config);
        }
    }
}