Build jdk11 desugared lib with jdk11

Change-Id: I5ba3118c2c94b64cfae292996a493d893d4d45d6
diff --git a/tools/archive_desugar_jdk_libs.py b/tools/archive_desugar_jdk_libs.py
index a44524e..a61ffad 100755
--- a/tools/archive_desugar_jdk_libs.py
+++ b/tools/archive_desugar_jdk_libs.py
@@ -98,7 +98,8 @@
         bazel,
         '--bazelrc=/dev/null',
         'build',
-        'maven_release' + ('_jdk11' if variant == 'jdk11' else '')]
+        'maven_release' + ('_jdk11' if variant == 'jdk11' else ''),
+         '--java_language_version=' + ('11' if variant == 'jdk11' else '8')]
     utils.PrintCmd(cmd)
     subprocess.check_call(cmd)
     cmd = [bazel, 'shutdown']