refactor: use constants and simplify conditional logic

src/main/java/org/keycloak/social/discord/DiscordIdentityProvider.java

@@ -131,11 +131,10 @@ public class DiscordIdentityProvider extends AbstractOAuth2IdentityProvider<Disc
             throw new IdentityBrokerException("Could not obtain user profile from discord.", e);
         }
 
-        if (getConfig().hasAllowedGuilds()) {
-            if (!isAllowedGuild(accessToken)) {
-                throw new ErrorPageException(session, Response.Status.FORBIDDEN, Messages.INVALID_REQUESTER);
-            }
+        if (getConfig().hasAllowedGuilds() && !isAllowedGuild(accessToken)) {
+            throw new ErrorPageException(session, Response.Status.FORBIDDEN, Messages.INVALID_REQUESTER);
         }
+
         return extractIdentityFromProfile(null, profile);
     }
 

src/main/java/org/keycloak/social/discord/DiscordIdentityProviderConfig.java

@@ -30,6 +30,9 @@ import java.util.stream.Collectors;
  */
 public class DiscordIdentityProviderConfig extends OAuth2IdentityProviderConfig {
 
+    public static final String ALLOWED_GUILDS = "allowedGuilds";
+    public static final String PROMPT = "prompt";
+
     public DiscordIdentityProviderConfig(IdentityProviderModel model) {
         super(model);
     }
@@ -38,27 +41,27 @@ public class DiscordIdentityProviderConfig extends OAuth2IdentityProviderConfig
     }
 
     public String getAllowedGuilds() {
-        return getConfig().get("allowedGuilds");
+        return getConfig().get(ALLOWED_GUILDS);
     }
 
     public void setAllowedGuilds(String allowedGuilds) {
-        getConfig().put("allowedGuilds", allowedGuilds);
+        getConfig().put(ALLOWED_GUILDS, allowedGuilds);
     }
 
     public boolean hasAllowedGuilds() {
-        String guilds = getConfig().get("allowedGuilds");
+        String guilds = getConfig().get(ALLOWED_GUILDS);
         return guilds != null && !guilds.trim().isEmpty();
     }
 
     public Set<String> getAllowedGuildsAsSet() {
         if (hasAllowedGuilds()) {
-            String guilds = getConfig().get("allowedGuilds");
+            String guilds = getConfig().get(ALLOWED_GUILDS);
             return Arrays.stream(guilds.split(",")).map(x -> x.trim()).collect(Collectors.toSet());
         }
         return Collections.emptySet();
     }
 
     public void setPrompt(String prompt) {
-        getConfig().put("prompt", prompt);
+        getConfig().put(PROMPT, prompt);
     }
 }