Add all the sources to //:srcs filegroup and add a check to detect
missing file to it.

We need to activate this check on presubmits

--
Change-Id: Ia95e92d3816ce92bb69bc0e2cf56e9c60b68d970
Reviewed-on: https://bazel-review.googlesource.com/#/c/3949/
MOS_MIGRATED_REVID=126404792
diff --git a/examples/java-native/BUILD b/examples/java-native/BUILD
index b698a88..4f4ecd1 100644
--- a/examples/java-native/BUILD
+++ b/examples/java-native/BUILD
@@ -2,7 +2,7 @@
 
 filegroup(
     name = "srcs",
-    srcs = [
+    srcs = glob(["**"]) + [
         "//examples/java-native/src/main/java/com/example/myproject:srcs",
         "//examples/java-native/src/main/resources:srcs",
         "//examples/java-native/src/test/java/com/example/myproject:srcs",