Java Double type covert to float64 panic when null value set.

[ma642]

What happened:
Java side:

class Score implements Serializable {
private Double score;
private String name;

public void setName(String name) {
    this.name = name;
}
public String getName() {
    return this.name;
}

public void setScore(Double score) {
    this.score = score;
}

public Double getScore() {
    return this.score;
}

}

.....
.....
Score s = new Score();
s.setScore(null);
s.setName("DoubleWithNull");

golang side:

type score struct {
Score float64
Name string
}

golang side get error when Double is null value as below

error:decDouble parse double wrong tag:78-0x4e\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decDouble\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/double.go:151\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decInstance\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/object.go:486\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decObject\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/object.go:696\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).DecodeValue\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/decode.go:285\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decObject\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/object.go:655\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).DecodeValue\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/decode.go:285\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).Decode\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/decode.go:214\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.unmarshalRequestBody\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/hessian.go:244\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.HessianSerializer.Unmarshal\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/hessian.go:56\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.(*ProtocolCodec).Decode\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/codec.go:186\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.(*DubboPackage).Unmarshal\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/package.go:93\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo.(*DubboCodec).decodeRequest\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/dubbo_codec.go:189\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo.(*DubboCodec).Decode\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/dubbo_codec.go:165\ndubbo.apache.org/dubbo-go/v3/remoting/getty.(*RpcServerPackageHandler).Read\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/remoting/getty/readwriter.go:104\ngithub.com/apache/dubbo-getty.(*session).handleTCPPackage\n\t/go/pkg/mod/github.com/apache/dubbo-getty@v1.4.5/session.go:627\ngithub.com/apache/dubbo-getty.(*session).handlePackage\n\t/go/pkg/mod/github.com/apache/dubbo-getty@v1.4.5/session.go:549\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1581\ndecInstance->decDouble field name:totalScore\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decInstance\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/object.go:488\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decObject\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/object.go:696\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).DecodeValue\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/decode.go:285\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).decObject\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/object.go:655\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).DecodeValue\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/decode.go:285\ngithub.com/apache/dubbo-go-hessian2.(*Decoder).Decode\n\t/go/pkg/mod/github.com/apache/dubbo-go-hessian2@v1.10.1-0.20211206111530-75ff95074949/decode.go:214\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.unmarshalRequestBody\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/hessian.go:244\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.HessianSerializer.Unmarshal\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/hessian.go:56\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.(*ProtocolCodec).Decode\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/codec.go:186\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo/impl.(*DubboPackage).Unmarshal\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/impl/package.go:93\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo.(*DubboCodec).decodeRequest\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/dubbo_codec.go:189\ndubbo.apache.org/dubbo-go/v3/protocol/dubbo.(*DubboCodec).Decode\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/protocol/dubbo/dubbo_codec.go:165\ndubbo.apache.org/dubbo-go/v3/remoting/getty.(*RpcServerPackageHandler).Read\n\t/go/pkg/mod/dubbo.apache.org/dubbo-go/v3@v3.0.0-rc4-1/remoting/getty/readwriter.go:104\ngithub.com/apache/dubbo-getty.(*session).handleTCPPackage\n\t/go/pkg/mod/github.com/apach

What you expected to happen:
zero value without error in golang code.
How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

[wongoo]

@ma642 pls provide more details, like struct definition, instance values, etc.