Merged with master (auth unit test improvements)

src/main/java/com/google/firebase/auth/FirebaseAuth.java

@@ -556,11 +556,7 @@ private CallableOperation<ListUsersPage, FirebaseAuthException> listUsersOp(
     return new CallableOperation<ListUsersPage, FirebaseAuthException>() {
       @Override
       protected ListUsersPage execute() throws FirebaseAuthException {
-        try {
-          return factory.create();
-        } catch (Exception e) {
-          throw new FirebaseAuthException(ERROR_LIST_USERS, "Error while retrieving user data", e);
-        }
+        return factory.create();
       }
     };
   }

src/test/java/com/google/firebase/auth/FirebaseUserManagerTest.java

@@ -316,7 +316,7 @@ public void call(FirebaseAuth auth) throws Exception {
           operation.call(FirebaseAuth.getInstance());
           fail("No error thrown for HTTP error: " + code);
         } catch (ExecutionException e) {
-          assertTrue(e.getCause().toString(), e.getCause() instanceof FirebaseAuthException);
+          assertTrue(e.getCause() instanceof FirebaseAuthException);
           FirebaseAuthException authException = (FirebaseAuthException) e.getCause();
           String msg = String.format("Unexpected HTTP response with status: %d; body: {}", code);
           assertEquals(msg, authException.getMessage());