Update README.md

Author: Chris Wiechmann

README.md

@@ -1,2 +1,88 @@
-# azure-oauth2provider
+# Azure OAuth2Provider
 
+If you use the API gateway as an OAuth2 client with Azure, it may be necessary to register a special OAuth2 provider. 
+Especially if you use the PKCE flow. The reason is that during the token exchange request Azure requires an Origin header and acknowledges this with the following error message:  
+`
+"error":"invalid_request","error_description":"AADSTS9002327: Tokens issued for the 'Single-Page Application' client-type may only be redeemed via cross-origin requests.\r\nTrace ID: 0e8f9824-95f5-481a-8deb-b035b1dd8303\r\nCorrelation ID: 2e1e8f7d-a08a-420e-8908-074c2a9add4d\r\nTimestamp: 2021-07-12 13:45:27Z","error_codes":[9002327],"timestamp":"2021-07-12 13:45:27Z","trace_id":"0e8f9824-95f5-481a-8deb-b035b1dd8303","correlation_id":"2e1e8f7d-a08a-420e-8908-074c2a9add4d"}
+`
+
+This Azure OAuth2Provider will add the required `Origin` header in the Token-Exchange request.
+
+![Dummy Origin header](https://github.com/Axway-API-Management-Plus/azure-oauth2provider/blob/main/lib/images/token_exchange_request_headers.png)
+
+# Installation & Setup
+
+- Download the release package
+- Copy the JAR-File into your API-Gateway(s) `ext/lib` folder and __restart the API-Gateway(s)__
+- If you don't have already, setup your OAuth-Client-Provider using Policy-Studio
+- Close the Policy-Studio project
+- Open Policy-Studio project file: `ExtConnsStore-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.xml`
+- Locate your configured Azure OAuthProviderProfile and changhe the `class` to `com.axway.oauth.client.providers.AzureOAuth2Provider` as in the example below
+- Re-Open the project in Policy-Studio and deploy the configuration
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<entity xmlns="http://www.vordel.com/2005/06/24/entityStore" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" type="OAuthProviderProfile" entityPK="6017837698390746166" parentPK="5256084280368879969">
+   <fval name="authzUrl">
+      <value>https://login.microsoftonline.com/........./oauth2/v2.0/authorize</value>
+   </fval>
+   <fval name="cacheToUse">
+      <value contentType="reference">
+         <key type="CacheManager">
+            <id field="name" value="Cache Manager" />
+            <key type="Cache">
+               <id field="name" value="OAuth Client State Cache" />
+            </key>
+         </key>
+      </value>
+   </fval>
+   <fval name="class">
+      <value>com.axway.oauth.client.providers.AzureOAuth2Provider</value>
+   </fval>
+   <fval name="name">
+      <value>Azure AD</value>
+   </fval>
+   <fval name="tokenStore">
+      <value contentType="reference">
+         <key type="OAuth2StoresGroup">
+            <id field="name" value="OAuth2 Stores" />
+            <key type="ClientAccessTokenStoreGroup">
+               <id field="name" value="Client Access Token Stores" />
+               <key type="ClientAccessTokenPersist">
+                  <id field="name" value="OAuth Client Access Token Store" />
+               </key>
+            </key>
+         </key>
+      </value>
+   </fval>
+   <fval name="tokenUrl">
+      <value>https://login.microsoftonline.com/........./oauth2/v2.0/token</value>
+   </fval>
+</entity>
+```
+
+## API Management Version Compatibilty
+
+This artefact has been tested with API-Management Versions
+
+| Version            | Comment         |
+| :---               | :---            |
+| 7.7-20210530       |                 |
+| 7.7-20210330       |                 |
+| 7.7-20200930       |                 |
+
+Please let us know, if you encounter any [issues](https://github.com/Axway-API-Management-Plus/openapi-validator/issues) with your API-Manager version.  
+
+## Contributing
+
+Please read [Contributing.md](https://github.com/Axway-API-Management-Plus/Common/blob/master/Contributing.md) for details on our code of conduct, and the process for submitting pull requests to us.
+
+## Team
+
+![alt text][Axwaylogo] Axway Team
+
+[Axwaylogo]: https://github.com/Axway-API-Management/Common/blob/master/img/AxwayLogoSmall.png  "Axway logo"
+
+
+## License
+[Apache License 2.0](/LICENSE)