Adds a test verifying that the Java backend is compatible with the C++ backend.

Change-Id: Ib9cfeeba049281f6bf96c42758864d9e6a800dfa
diff --git a/Coordinator.cpp b/Coordinator.cpp
index 90308de..2421427 100644
--- a/Coordinator.cpp
+++ b/Coordinator.cpp
@@ -165,7 +165,8 @@
             break;
         }
     }
-    CHECK(it != mPackageRoots.end());
+    CHECK(it != mPackageRoots.end())
+        << "Unable to find package root for " << fqName.string();
 
     return it;
 }