SpanContext can put in MDC #179
Description
Suppose this situation:
when i use tracing system,and i find a trace has a problem. So,i search the logs in ELK .But ,i find it is so hard to search the logs related to that trace,because there is no trace id in logs.So i can not find related logs by trace id.
so，colud put SpanContext(include traceId,spanId,parentId,flag) in MDC,i can format the log from the MDC.And then I can search the log by trace id