Add module annotation to specify the name of the java class for constants.

mojo/public/interfaces/bindings/tests/sample_interfaces.mojom

Index: mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
diff --git a/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom b/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
index f2b1dc93dcac3ed6e2cb0a1913eeee5b09309832..429520fa9b98792f9d85c35fa88fff991bba0cf7 100644
--- a/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
+++ b/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
@@ -3,9 +3,12 @@
 // found in the LICENSE file.
 
 [JavaPackage="org.chromium.mojo.bindings.test.sample",
+ JavaConstantsClassName="InterfaceConstants",
  Foo = "hello world"]
 module sample {
 
+const uint64 kLong = 4405;
+
 enum Enum {
   ENUM_VALUE
 };