+ README Changes

Author: snavinch

README.md

@@ -46,6 +46,10 @@ The API Reference Guide provides examples of what information is needed for a pa
 ## MetaKey Support
 Meta Key is a key generated by an entity that can be used to authenticate on behalf of other entities provided that the entity which holds key is a parent entity or associated as a partner.
 
+## OAuth Support
+The CyberSource OAuth2.0 Authorization Server (or API Auth Service) will issue access tokens (based on merchant user credentials) to CyberSource or third-party Applications. These applications can access CyberSource API's on the merchant's behalf, using the access tokens.
+During application registration, third-party application developers are issued a client_id and optionally a client_secret (if they can be considered a confidential client, for example a web application). Requesting an access token is fairly straightforward:  Use the CyberSource token URL and include a set of form-urlencoded parameters.
+Upon receipt of this request, the CyberSource Authorization Server validates the user credentials, then mints and returns a response to your application. The contents of this response depend on the type of application. For web server applications, the response is an authorization code which can be exchanged for an access token and (optionally) a refresh token. For client-side applications (e.g. mobile apps), the response is an access token.  [For the Resource Owner Password Flow, only the latter response is returned.]
 
 ### Switching between the sandbox environment and the production environment
 Cybersource maintains a complete sandbox environment for testing and development purposes. This sandbox environment is an exact duplicate of our production environment with the transaction authorization and settlement process simulated. By default, this SDK is configured to communicate with the sandbox environment. To switch to the production environment, set the `runEnvironment` property in the SDK Configuration.  See our sample at https://github.com/CyberSource/cybersource-rest-samples-java/blob/master/src/main/java/Data/Configuration.java.