diff --git a/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldClientTest.java b/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldClientTest.java
index e69bc05dfe99..bd605eefffbf 100644
--- a/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldClientTest.java
+++ b/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldClientTest.java
@@ -39,6 +39,10 @@
  * For demonstrating how to write gRPC unit test only.
  * Not intended to provide a high code coverage or to test every major usecase.
  *
+ * Note we use directExecutor() here to speed up the test
+ * but this requires the application to not block under any circumstances.
+ * Particilarly in bidirectional streaming it's better to use the default executor!
+ *
  * <p>For more unit test examples see {@link io.grpc.examples.routeguide.RouteGuideClientTest} and
  * {@link io.grpc.examples.routeguide.RouteGuideServerTest}.
  */
diff --git a/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldServerTest.java b/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldServerTest.java
index 46d39559942e..ccb3aab1d6bb 100644
--- a/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldServerTest.java
+++ b/examples/src/test/java/io/grpc/examples/helloworld/HelloWorldServerTest.java
@@ -32,6 +32,10 @@
  * For demonstrating how to write gRPC unit test only.
  * Not intended to provide a high code coverage or to test every major usecase.
  *
+ * Note we use directExecutor() here to speed up the test
+ * but this requires the application to not block under any circumstances.
+ * Particilarly in bidirectional streaming it's better to use the default executor!
+ *
  * <p>For more unit test examples see {@link io.grpc.examples.routeguide.RouteGuideClientTest} and
  * {@link io.grpc.examples.routeguide.RouteGuideServerTest}.
  */
diff --git a/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideClientTest.java b/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideClientTest.java
index 531892808dc2..eaeb4eaecf3b 100644
--- a/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideClientTest.java
+++ b/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideClientTest.java
@@ -53,6 +53,10 @@
  * For demonstrating how to write gRPC unit test only.
  * Not intended to provide a high code coverage or to test every major usecase.
  *
+ * Note we use directExecutor() here to speed up the test
+ * but this requires the application to not block under any circumstances.
+ * Particilarly in bidirectional streaming it's better to use the default executor!
+ *
  * <p>For basic unit test examples see {@link io.grpc.examples.helloworld.HelloWorldClientTest} and
  * {@link io.grpc.examples.helloworld.HelloWorldServerTest}.
  */
diff --git a/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideServerTest.java b/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideServerTest.java
index 01013415d27d..ac732d15d30d 100644
--- a/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideServerTest.java
+++ b/examples/src/test/java/io/grpc/examples/routeguide/RouteGuideServerTest.java
@@ -49,6 +49,10 @@
  * For demonstrating how to write gRPC unit test only.
  * Not intended to provide a high code coverage or to test every major usecase.
  *
+ * Note we use directExecutor() here to speed up the test
+ * but this requires the application to not block under any circumstances.
+ * Particilarly in bidirectional streaming it's better to use the default executor!
+ *
  * <p>For basic unit test examples see {@link io.grpc.examples.helloworld.HelloWorldClientTest} and
  * {@link io.grpc.examples.helloworld.HelloWorldServerTest}.
  */