add grpc-core to BOM (googleapis#2931)

pongad · web-flow · commit b681031457f5 · 2018-02-22T10:34:48.000+11:00
Fixes googleapis#2924.
diff --git a/google-cloud-bom/pom.xml b/google-cloud-bom/pom.xml
@@ -902,6 +902,11 @@
         <artifactId>api-common</artifactId>
         <version>${api-common.version}</version>
       </dependency>
+      <dependency>
+        <groupId>io.grpc</groupId>
+        <artifactId>grpc-core</artifactId>
+        <version>${grpc.version}</version>
+      </dependency>
       <dependency>
         <groupId>io.grpc</groupId>
         <artifactId>grpc-netty</artifactId>
