Add warning about the dangers of the blocking client methods

src/ConfigCatClient/IConfigCatClient.cs

@@ -23,6 +23,11 @@ public interface IConfigCatClient : IProvidesHooks, IDisposable
     /// It is important to provide an argument for the <paramref name="defaultValue"/> parameter, specifically for the <typeparamref name="T"/> generic type parameter,
     /// that matches the type of the feature flag or setting you are evaluating.<br/>
     /// Please refer to <see href="https://configcat.com/docs/sdk-reference/dotnet/#setting-type-mapping">this table</see> for the corresponding types.
+    /// <para>
+    /// Please be aware that calling this method on a thread pool thread or the main UI thread is safe only when the client is set up to use Auto or Manual Polling and in-memory caching.
+    /// Otherwise execution may involve I/O-bound (e.g. network) operations. Thus, the executing thread may be blocked for a longer period of time, which can result in an unresponsive application.
+    /// In the case of problematic setups, it is recommended to use the async version of this method or snaphots (see <see cref="Snapshot"/>).
+    /// </para>
     /// </remarks>
     /// <typeparam name="T">
     /// The type of the value. Only the following types are allowed:
@@ -69,6 +74,11 @@ public interface IConfigCatClient : IProvidesHooks, IDisposable
     /// It is important to provide an argument for the <paramref name="defaultValue"/> parameter, specifically for the <typeparamref name="T"/> generic type parameter,
     /// that matches the type of the feature flag or setting you are evaluating.<br/>
     /// Please refer to <see href="https://configcat.com/docs/sdk-reference/dotnet/#setting-type-mapping">this table</see> for the corresponding types.
+    /// <para>
+    /// Please be aware that calling this method on a thread pool thread or the main UI thread is safe only when the client is set up to use Auto or Manual Polling and in-memory caching.
+    /// Otherwise execution may involve I/O-bound (e.g. network) operations. Thus, the executing thread may be blocked for a longer period of time, which can result in an unresponsive application.
+    /// In the case of problematic setups, it is recommended to use the async version of this method or snaphots (see <see cref="Snapshot"/>).
+    /// </para>
     /// </remarks>
     /// <typeparam name="T">
     /// The type of the value. Only the following types are allowed:
@@ -111,6 +121,13 @@ public interface IConfigCatClient : IProvidesHooks, IDisposable
     /// <summary>
     /// Returns all setting keys synchronously.
     /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Please be aware that calling this method on a thread pool thread or the main UI thread is safe only when the client is set up to use Auto or Manual Polling and in-memory caching.
+    /// Otherwise execution may involve I/O-bound (e.g. network) operations. Thus, the executing thread may be blocked for a longer period of time, which can result in an unresponsive application.
+    /// In the case of problematic setups, it is recommended to use the async version of this method or snaphots (see <see cref="Snapshot"/>).
+    /// </para>
+    /// </remarks>
     /// <returns>The collection of keys.</returns>
     IReadOnlyCollection<string> GetAllKeys();
 
@@ -124,6 +141,13 @@ public interface IConfigCatClient : IProvidesHooks, IDisposable
     /// <summary>
     /// Returns the keys and values of all feature flags and settings synchronously.
     /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Please be aware that calling this method on a thread pool thread or the main UI thread is safe only when the client is set up to use Auto or Manual Polling and in-memory caching.
+    /// Otherwise execution may involve I/O-bound (e.g. network) operations. Thus, the executing thread may be blocked for a longer period of time, which can result in an unresponsive application.
+    /// In the case of problematic setups, it is recommended to use the async version of this method or snaphots (see <see cref="Snapshot"/>).
+    /// </para>
+    /// </remarks>
     /// <param name="user">The User Object to use for evaluating targeting rules and percentage options.</param>
     /// <returns>The dictionary containing the keys and values.</returns>
     IReadOnlyDictionary<string, object?> GetAllValues(User? user = null);
@@ -139,6 +163,13 @@ public interface IConfigCatClient : IProvidesHooks, IDisposable
     /// <summary>
     /// Returns the values along with evaluation details of all feature flags and settings synchronously.
     /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Please be aware that calling this method on a thread pool thread or the main UI thread is safe only when the client is set up to use Auto or Manual Polling and in-memory caching.
+    /// Otherwise execution may involve I/O-bound (e.g. network) operations. Thus, the executing thread may be blocked for a longer period of time, which can result in an unresponsive application.
+    /// In the case of problematic setups, it is recommended to use the async version of this method or snaphots (see <see cref="Snapshot"/>).
+    /// </para>
+    /// </remarks>
     /// <param name="user">The User Object to use for evaluating targeting rules and percentage options.</param>
     /// <returns>The list of values along with evaluation details.</returns>
     IReadOnlyList<EvaluationDetails> GetAllValueDetails(User? user = null);
@@ -154,6 +185,13 @@ public interface IConfigCatClient : IProvidesHooks, IDisposable
     /// <summary>
     /// Refreshes the locally cached config by fetching the latest version from the remote server synchronously.
     /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Please be aware that calling this method on a thread pool thread or the main UI thread is not safe because
+    /// execution involve I/O-bound (e.g. network) operations. Thus, the executing thread may be blocked for a longer period of time, which can result in an unresponsive application.
+    /// In the case of problematic setups, it is recommended to use the async version of this method.
+    /// </para>
+    /// </remarks>
     /// <returns>The refresh result.</returns>
     RefreshResult ForceRefresh();