public Builder toBuilder() {
        return this == DEFAULT_INSTANCE
            ? new Builder() : new Builder().mergeFrom(this);
    }
<code>.com.alipay.sofa.rpc.server.bolt.pb.Group group = 2;</code>
test/test-integration/src/test/java/com/alipay/sofa/rpc/server/bolt/pb/EchoRequest.java