examples: Fix RequireUpperBoundDeps

Author: ejona86

examples/example-debug/pom.xml

@@ -55,6 +55,11 @@
       <artifactId>grpc-netty-shaded</artifactId>
       <scope>runtime</scope>
     </dependency>
+    <dependency> <!-- prevent downgrade of version in protobuf-java-util from grpc-services -->
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>31.1-jre</version>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>

examples/example-hostname/pom.xml

@@ -55,6 +55,11 @@
       <artifactId>grpc-netty-shaded</artifactId>
       <scope>runtime</scope>
     </dependency>
+    <dependency> <!-- prevent downgrade of version in protobuf-java-util from grpc-services -->
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>31.1-jre</version>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>

examples/pom.xml

@@ -60,6 +60,11 @@
       <artifactId>gson</artifactId>
       <version>2.9.0</version> <!-- prevent downgrade via protobuf-java-util -->
     </dependency>
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>31.1-jre</version> <!-- prevent downgrade of version in protobuf-java-util -->
+    </dependency>
     <dependency>
       <groupId>org.apache.tomcat</groupId>
       <artifactId>annotations-api</artifactId>