OAUTH-3319 Fix and update field names in OpenIdDiscovery.java according to OpenID specification

src/main/java/com/onegini/oidc/model/OpenIdDiscovery.java

@@ -9,6 +9,7 @@ import lombok.NoArgsConstructor;
 @NoArgsConstructor
 public class OpenIdDiscovery {
 
+  //required and recommended
   private String issuer;
   private String authorizationEndpoint;
   private String tokenEndpoint;
@@ -16,14 +17,20 @@ public class OpenIdDiscovery {
   private String userinfoEndpoint;
   private Collection<String> responseTypesSupported;
   private Collection<String> subjectTypesSupported;
-  private Collection<String> idTokenSigningAlgValues;
+  private Collection<String> idTokenSigningAlgValuesSupported;
+  private Collection<String> tokenEndpointAuthMethodsSupported;
   private Collection<String> scopesSupported;
   private Collection<String> claimsSupported;
+
+  //optional but needed for SSO
   private String checkSessionIframe;
   private String endSessionEndpoint;
   private boolean frontchannelLogoutSupported;
   private boolean frontchannelLogoutSessionSupported;
+
+  //optional
   private Collection<String> idTokenEncryptionAlgValuesSupported;
   private Collection<String> idTokenEncryptionEncValuesSupported;
+  private Collection<String> acrValuesSupported;
 
 }
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