Java中的Dgraph。如何运行原始字符串突变查询？

import io.dgraph.DgraphClient;
import io.dgraph.DgraphClientBuilder;
import io.dgraph.Mutation;
import io.dgraph.Transaction;

public class DgraphMutationExample {
    public static void main(String[] args) {
        // 创建 Dgraph 客户端
        DgraphClient dgraphClient = new DgraphClientBuilder().build();

        // 创建一个突变操作
        String mutationString = "_:node <name> \"John\" .";
        Mutation mutation = Mutation.newBuilder().setSetJson(mutationString).build();

        // 创建事务
        Transaction transaction = dgraphClient.newTransaction();

        try {
            // 执行突变操作
            transaction.mutate(mutation);

            // 提交事务
            transaction.commit();
        } finally {
            // 关闭事务
            transaction.close();
        }
    }
}