Java delete dql

Documentation
1

my code is :

        DgraphProto.Mutation mu = DgraphProto.Mutation.newBuilder().build();
        mu = Helpers.deleteEdges(mu, "0x9a3", "biz_constraint.actions");
        DgraphProto.Response response = client.newTransaction().mutate(mu);

Can you tell me where is the error

2

Are you using .setCommitNow(true)? or txn.commit() in a transaction?