Bump protoc-gen-grpc-java from 1.21.0 to 1.22.1

Bumps [protoc-gen-grpc-java](https://github.com/grpc/grpc-java) from 1.21.0 to 1.22.1.
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.21.0...v1.22.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

examples/java/build.gradle

@@ -13,7 +13,7 @@ protobuf {
 
     plugins {
         grpc {
-            artifact = 'io.grpc:protoc-gen-grpc-java:1.21.0'
+            artifact = 'io.grpc:protoc-gen-grpc-java:1.22.1'
         }
 
         reactor {