Why would a spanId becomes a child of itself in jaeger-client-go

[zyxue]

I described the problem in more detail at SeldonIO/seldon-core#3889.

In short, with propagation set to b3, I see traces like

            "spans": [
                {
                    "traceID": "11111111111111111111111111111116",
                    "spanID": "1111111111111116",
                    "flags": 1,
                    "operationName": "/seldon.protos.Seldon/Predict",
                    "references": [
                        {
                            "refType": "CHILD_OF",
                            "traceID": "11111111111111111111111111111116",
                            "spanID": "2222222222222226"
                        },
                        {
                            "refType": "CHILD_OF",
                            "traceID": "11111111111111111111111111111116",
                            "spanID": "1111111111111116"
                        }
                    ],

where span id 1111111111111116 is a child of itself.

Because seldon executor uses jaeger-client-go v2.25.0, I wonder if it can be an issue with jaeger-client-go, and what could be the possible cause?