diff --git a/compiler/src/java_plugin/cpp/java_generator.cpp b/compiler/src/java_plugin/cpp/java_generator.cpp
index 54c6067..8a65b06 100644
--- a/compiler/src/java_plugin/cpp/java_generator.cpp
+++ b/compiler/src/java_plugin/cpp/java_generator.cpp
@@ -297,6 +297,7 @@
   if (abstract) {
     p->Print(
         *vars,
+        "@$ExperimentalApi$\n"
         "public static abstract class $abstract_name$ implements $service_name$, "
         "$BindableService$ {\n");
   } else if (!impl) {
diff --git a/compiler/src/test/golden/TestService.java.txt b/compiler/src/test/golden/TestService.java.txt
index ac6db78..57691bf 100644
--- a/compiler/src/test/golden/TestService.java.txt
+++ b/compiler/src/test/golden/TestService.java.txt
@@ -103,6 +103,7 @@
         io.grpc.stub.StreamObserver<io.grpc.testing.integration.Test.StreamingOutputCallResponse> responseObserver);
   }
 
+  @io.grpc.ExperimentalApi
   public static abstract class AbstractTestService implements TestService, io.grpc.BindableService {
 
     @java.lang.Override
diff --git a/compiler/src/testLite/golden/TestService.java.txt b/compiler/src/testLite/golden/TestService.java.txt
index cb76da8..31002c9 100644
--- a/compiler/src/testLite/golden/TestService.java.txt
+++ b/compiler/src/testLite/golden/TestService.java.txt
@@ -103,6 +103,7 @@
         io.grpc.stub.StreamObserver<io.grpc.testing.integration.Test.StreamingOutputCallResponse> responseObserver);
   }
 
+  @io.grpc.ExperimentalApi
   public static abstract class AbstractTestService implements TestService, io.grpc.BindableService {
 
     @java.lang.Override
diff --git a/compiler/src/testNano/golden/TestService.java.txt b/compiler/src/testNano/golden/TestService.java.txt
index ccd028e..1f2c91c 100644
--- a/compiler/src/testNano/golden/TestService.java.txt
+++ b/compiler/src/testNano/golden/TestService.java.txt
@@ -181,6 +181,7 @@
         io.grpc.stub.StreamObserver<io.grpc.testing.integration.nano.Test.StreamingOutputCallResponse> responseObserver);
   }
 
+  @io.grpc.ExperimentalApi
   public static abstract class AbstractTestService implements TestService, io.grpc.BindableService {
 
     @java.lang.Override