tests.baz@1.0: changes for symmetric tests

Changes to make hidl_test_java symmetric (this implementation mirrors
one in system/tools/hidl).

Bug: 168152294
Test: atest hidl_test_java
Change-Id: I29a468d1804ba494bfe5ca59d68b3ab2581eb9b4
diff --git a/tests/baz/1.0/IBase.hal b/tests/baz/1.0/IBase.hal
index 0c1b61f..7b60a8a 100644
--- a/tests/baz/1.0/IBase.hal
+++ b/tests/baz/1.0/IBase.hal
@@ -101,6 +101,8 @@
         DoubleThreeDim double3;
     };
 
+    isJava() generates (bool isJava);
+
     someBaseMethod();
 
     someBoolMethod(bool x) generates (bool y);