Update RegisteredClient.Builder to use getters

- Since the class is not final, it is possible to extend it.
  Because the Builder was directly accessing the properties
  rather than using the getters, it was not possible to use
  the .from(id) constructor in the extended class.

Closes spring-projectsgh-451

Author: sarahwalther

oauth2-authorization-server/src/main/java/org/springframework/security/oauth2/server/authorization/client/RegisteredClient.java

@@ -262,23 +262,23 @@ protected Builder(String id) {
 		}
 
 		protected Builder(RegisteredClient registeredClient) {
-			this.id = registeredClient.id;
-			this.clientId = registeredClient.clientId;
-			this.clientIdIssuedAt = registeredClient.clientIdIssuedAt;
-			this.clientSecret = registeredClient.clientSecret;
-			this.clientSecretExpiresAt = registeredClient.clientSecretExpiresAt;
-			this.clientName = registeredClient.clientName;
-			if (!CollectionUtils.isEmpty(registeredClient.clientAuthenticationMethods)) {
-				this.clientAuthenticationMethods.addAll(registeredClient.clientAuthenticationMethods);
+			this.id = registeredClient.getId();
+			this.clientId = registeredClient.getClientId();
+			this.clientIdIssuedAt = registeredClient.getClientIdIssuedAt();
+			this.clientSecret = registeredClient.getClientSecret();
+			this.clientSecretExpiresAt = registeredClient.getClientSecretExpiresAt();
+			this.clientName = registeredClient.getClientName();
+			if (!CollectionUtils.isEmpty(registeredClient.getClientAuthenticationMethods())) {
+				this.clientAuthenticationMethods.addAll(registeredClient.getClientAuthenticationMethods());
 			}
-			if (!CollectionUtils.isEmpty(registeredClient.authorizationGrantTypes)) {
-				this.authorizationGrantTypes.addAll(registeredClient.authorizationGrantTypes);
+			if (!CollectionUtils.isEmpty(registeredClient.getAuthorizationGrantTypes())) {
+				this.authorizationGrantTypes.addAll(registeredClient.getAuthorizationGrantTypes());
 			}
-			if (!CollectionUtils.isEmpty(registeredClient.redirectUris)) {
-				this.redirectUris.addAll(registeredClient.redirectUris);
+			if (!CollectionUtils.isEmpty(registeredClient.getRedirectUris())) {
+				this.redirectUris.addAll(registeredClient.getRedirectUris());
 			}
-			if (!CollectionUtils.isEmpty(registeredClient.scopes)) {
-				this.scopes.addAll(registeredClient.scopes);
+			if (!CollectionUtils.isEmpty(registeredClient.getScopes())) {
+				this.scopes.addAll(registeredClient.getScopes());
 			}
 			this.clientSettings = ClientSettings.withSettings(registeredClient.getClientSettings().getSettings()).build();
 			this.tokenSettings = TokenSettings.withSettings(registeredClient.getTokenSettings().getSettings()).build();