chore: adding cloud-rad java xrefs (#444)

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Source-Link: googleapis/synthtool@046994f

.kokoro/release/publish_javadoc11.sh

@@ -49,6 +49,13 @@ pushd target/docfx-yml
 python3 -m docuploader create-metadata \
  --name ${NAME} \
  --version ${VERSION} \
+ --xrefs devsite://java/gax \
+ --xrefs devsite://java/google-cloud-core \
+ --xrefs devsite://java/api-common \
+ --xrefs devsite://java/proto-google-common-protos \
+ --xrefs devsite://java/google-api-client \
+ --xrefs devsite://java/google-http-client \
+ --xrefs devsite://java/protobuf \
  --language java
 
 # upload yml to production bucket

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-core.git",
-        "sha": "c282c378e204b42e895d73f68a3c2d56a5da30d1"
+        "sha": "9685b00860e313cdaedc122428144017dd0c50c8"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "8285c2b4cdbc3771d031ad91e1c4ec9e55fff45d"
+        "sha": "046994f491c02806aea60118e214a9edd67f5ab7"
       }
     }
   ],