support const in parcelable/union

const values are now available in parcelable/union as well as interface.

Bug: 173225412
Test: CtsNdkBinderTestCases
Test: aidl_unittests
Test: aidl_integration_test
Change-Id: Ifab53c6b0e6674710f1206b7d2e2ca677d5430c6
diff --git a/generate_java.h b/generate_java.h
index 3ed2546..90553e4 100644
--- a/generate_java.h
+++ b/generate_java.h
@@ -44,6 +44,9 @@
 
 std::vector<std::string> generate_java_annotations(const AidlAnnotatable& a);
 
+void generate_constant_declarations(
+    CodeWriter& out, const std::vector<std::unique_ptr<AidlConstantDeclaration>>& constants);
+
 }  // namespace java
 }  // namespace aidl
 }  // namespace android