api: Add InitialSnapshot.realmTopicsPolicy

Author: chungwwei

lib/api/model/initial_snapshot.dart

@@ -90,6 +90,8 @@ class InitialSnapshot {
   /// Search for "realm_wildcard_mention_policy" in https://zulip.com/api/register-queue.
   final RealmWildcardMentionPolicy realmWildcardMentionPolicy;
 
+  final RealmTopicsPolicy? realmTopicsPolicy; // TODO(server-11)
+
   final bool realmMandatoryTopics;
 
   final String realmName;
@@ -183,6 +185,7 @@ class InitialSnapshot {
     required this.realmCanDeleteOwnMessageGroup,
     required this.realmDeleteOwnMessagePolicy,
     required this.realmWildcardMentionPolicy,
+    required this.realmTopicsPolicy,
     required this.realmMandatoryTopics,
     required this.realmName,
     required this.realmWaitingPeriodThreshold,
@@ -238,6 +241,23 @@ enum RealmDeleteOwnMessagePolicy {
   int toJson() => apiValue;
 }
 
+/// A value of [InitialSnapshot.realmTopicsPolicy].
+///
+/// For docs, search for "realm_topics_policy"
+/// in <https://zulip.com/api/register-queue#response>.
+@JsonEnum(fieldRename: FieldRename.snake, valueField: 'apiValue')
+enum RealmTopicsPolicy {
+  allowEmptyTopic(apiValue: 'allow_empty_topic'),
+  disableEmptyTopic(apiValue: 'disable_empty_topic'),
+  unknown(apiValue: null);
+
+  const RealmTopicsPolicy({required this.apiValue});
+
+  final String? apiValue;
+
+  String? toJson() => apiValue;
+}
+
 /// An item in `realm_default_external_accounts`.
 ///
 /// For docs, search for "realm_default_external_accounts:"

lib/api/model/initial_snapshot.g.dart

@@ -1335,6 +1335,7 @@ InitialSnapshot initialSnapshot({
   GroupSettingValue? realmCanDeleteOwnMessageGroup,
   RealmDeleteOwnMessagePolicy? realmDeleteOwnMessagePolicy,
   RealmWildcardMentionPolicy? realmWildcardMentionPolicy,
+  RealmTopicsPolicy? realmTopicsPolicy,
   bool? realmMandatoryTopics,
   String? realmName,
   int? realmWaitingPeriodThreshold,
@@ -1399,6 +1400,7 @@ InitialSnapshot initialSnapshot({
     realmCanDeleteOwnMessageGroup: realmCanDeleteOwnMessageGroup,
     realmDeleteOwnMessagePolicy: realmDeleteOwnMessagePolicy,
     realmWildcardMentionPolicy: realmWildcardMentionPolicy ?? RealmWildcardMentionPolicy.everyone,
+    realmTopicsPolicy: realmTopicsPolicy ?? RealmTopicsPolicy.allowEmptyTopic,
     realmMandatoryTopics: realmMandatoryTopics ?? true,
     realmName: realmName ?? 'Example Zulip organization',
     realmWaitingPeriodThreshold: realmWaitingPeriodThreshold ?? 0,