Add dependency on commons-lang3

Gerrit core removed commons-lang3 dependency from plugin API so that we
need to add it ourself in the build toolchain.

Bug: Issue 9253
Change-Id: I7120977be3d5f4a8fa5df4b439a81f25575fb811
diff --git a/BUILD b/BUILD
index 58e65ad..c11b095 100644
--- a/BUILD
+++ b/BUILD
@@ -46,6 +46,7 @@
     exports = [
         "@autolink//jar",
         "@cm_autolink//jar",
+        "@commons-lang3//jar",
         "@commonmark//jar",
         "@gfm_strikethrough//jar",
         "@gfm_tables//jar",
diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 45cec0a..58de043 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -19,6 +19,12 @@
 
   # commonmark must match the version used in Gitiles
   maven_jar(
+    name = 'commons-lang3',
+    artifact = 'org.apache.commons:commons-lang3:3.7',
+    sha1 = '557edd918fd41f9260963583ebf5a61a43a6b423',
+  )
+
+  maven_jar(
     name = 'commonmark',
     artifact = 'com.atlassian.commonmark:commonmark:' + COMMONMARK_VERSION,
     sha1 = '4eb11e3f9aaecafc6073b84c15f66376ef8dc5d3',