Accessing AzureAD API using google OAuth2 client library for java - google-oauth-java-client

Question

My project requires integration with G-Suite and AzureAD directory. Both of them supports OAuth2 as explained here and here.
I want to access G-Suite and AzueAD API with Google OAuth2 client. I have few questions for the same
Is it possible to access AzureAD API using google-oauth-api-client?
Is there any library which can be used with G-Suite SDK and AzureAD?
I don't want to separate library for each provider I integrate. Be it G-Suite or AzureAD or SalesForce or something else which supports OAuth2.

Answer 1

The Google OAuth2 client library can be used to authenticate against any OAuth2 provider by adding the following two classes:
public class ClientUsernamePasswordTokenRequest extends TokenRequest {
/**
* #param transport HTTP transport
* #param jsonFactory JSON factory
* #param tokenServerUrl token server URL
* #param grantType grant type ({#code "authorization_code"}, {#code "password"},
* {#code "client_credentials"}, {#code "refresh_token"} or absolute URI of the extension
*/
public ClientUsernamePasswordTokenRequest(HttpTransport transport, JsonFactory jsonFactory, GenericUrl tokenServerUrl, String grantType) {
super(transport, jsonFactory, tokenServerUrl, grantType);
}
#Override
public TokenResponse execute() throws IOException {
return convertStringToObject(executeUnparsed().parseAs(Map.class));
}
private TokenResponse convertStringToObject(Map content) {
TokenResponse tokenResponse = new TokenResponse();
String tokenType = (String) content.get("token_type");
tokenResponse.setTokenType(tokenType);
String scope = (String) content.get("scope");
tokenResponse.setScope(scope);
String accessToken = (String) content.get("access_token");
tokenResponse.setAccessToken(accessToken);
String refreshToken = (String) content.get("refresh_token");
tokenResponse.setRefreshToken(refreshToken);
return tokenResponse;
}
}
and
package com.identityforge.idfserver.backend.rest.auth;
import com.google.api.client.http.HttpExecuteInterceptor;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.UrlEncodedContent;
import com.google.api.client.util.Data;
import com.google.api.client.util.Preconditions;
import java.util.Map;
public class ClientParametersAuthentication implements HttpRequestInitializer, HttpExecuteInterceptor {
/**
* Client identifier issued to the client during the registration process.
*/
private final String clientId;
/**
* Client password or {#code null} for none.
*/
private final String password;
/**
* Client username
*/
private final String username;
/**
* Resource for which access is requested
*/
private final String resource;
private final String clientSecret;
/**
* #param clientId client identifier issued to the client during the registration process
* #param password password or {#code null} for none
* #param username
* #param resource
* #param clientSecret
*/
public ClientParametersAuthentication(String clientId, String password, String username, String resource, String clientSecret) {
this.clientId = Preconditions.checkNotNull(clientId);
this.password = Preconditions.checkNotNull(password);
this.username = Preconditions.checkNotNull(username);
this.resource = resource;
this.clientSecret = clientSecret;
}
public void initialize(HttpRequest request) {
request.setInterceptor(this);
}
public void intercept(HttpRequest request) {
Map<String, Object> data = Data.mapOf(UrlEncodedContent.getContent(request).getData());
data.put("client_id", clientId);
data.put("password", password);
data.put("username", username);
if (resource != null)
data.put("resource", resource);
if (clientSecret != null) {
data.put("client_secret", clientSecret);
}
}
}
Now access token can be requested by providing credentials values in the following code
private void fetchToken() throws IOException {
TokenResponse tokenResponse;
if (genericUrl == null) {
genericUrl = new GenericUrl(tokenUrl);
}
if (authentication == null) {
authentication = new ClientParametersAuthentication(clientId, passwd, username, resource, clientSecret);
}
if (tokenRequest == null) {
tokenRequest = new ClientUsernamePasswordTokenRequest(new ApacheHttpTransport(), JacksonFactory.getDefaultInstance(), genericUrl, grantType);
tokenRequest.setClientAuthentication(authentication);
}
tokenResponse = tokenRequest.execute();
String accessToken = tokenResponse.getAccessToken();
}
Here tokenUrl is the authentication endpoint.