Upgrade guava to 28.2-jre

Change-Id: Ia5876ce091358a90328e221cf633259cad6738b6

lib/guava.bzl

diff --git a/lib/guava.bzl b/lib/guava.bzl
index 18a8355..86060d4 100644
--- a/lib/guava.bzl
+++ b/lib/guava.bzl
@@ -1,5 +1,5 @@
-GUAVA_VERSION = "28.1-jre"
+GUAVA_VERSION = "28.2-jre"
 
-GUAVA_BIN_SHA1 = "b0e91dcb6a44ffb6221b5027e12a5cb34b841145"
+GUAVA_BIN_SHA1 = "8ec9ed76528425762174f0011ce8f74ad845b756"
 
 GUAVA_DOC_URL = "https://google.github.io/guava/releases/" + GUAVA_VERSION + "/api/docs/"