Upgrade guava to 28.0-jre

Change-Id: Ifa01de5b5851556d5ee26b9c7a8a4e4d8746eb8d
diff --git a/WORKSPACE b/WORKSPACE
index a1eaffd..5f6de1d 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -46,8 +46,8 @@
 
 maven_jar(
     name = "guava",
-    artifact = "com.google.guava:guava:27.1-jre",
-    sha1 = "e47b59c893079b87743cdcfb6f17ca95c08c592c",
+    artifact = "com.google.guava:guava:28.0-jre",
+    sha1 = "54fed371b4b8a8cce1e94a9abd9620982d3aa54b",
 )
 
 maven_jar(