Test Case:

0. start zipkin
1. start application
2. curl http://localhost:8080/

Expected Result:

Only one span was created

Actual Result

Five spans were created. One for the web request and one for each Mono.subscribeOn(), Mono.publishOn() (there are 4)

Zipkin output

[
  {
    "traceId": "47f9e42180743ba8",
    "parentId": "47f9e42180743ba8",
    "id": "000d90be78278f4c",
    "name": "async",
    "timestamp": 1552842670048458,
    "duration": 10632,
    "localEndpoint": {
      "serviceName": "async-span",
      "ipv4": "10.238.10.120"
    }
  },
  {
    "traceId": "47f9e42180743ba8",
    "parentId": "47f9e42180743ba8",
    "id": "e1cd31561a3578dd",
    "name": "async",
    "timestamp": 1552842670059121,
    "duration": 10631,
    "localEndpoint": {
      "serviceName": "async-span",
      "ipv4": "10.238.10.120"
    }
  },
  {
    "traceId": "47f9e42180743ba8",
    "parentId": "47f9e42180743ba8",
    "id": "aca3caf889fd694a",
    "name": "async",
    "timestamp": 1552842670069966,
    "duration": 11159,
    "localEndpoint": {
      "serviceName": "async-span",
      "ipv4": "10.238.10.120"
    }
  },
  {
    "traceId": "47f9e42180743ba8",
    "parentId": "47f9e42180743ba8",
    "id": "c7b4941f6264297b",
    "name": "async",
    "timestamp": 1552842670080822,
    "duration": 12677,
    "localEndpoint": {
      "serviceName": "async-span",
      "ipv4": "10.238.10.120"
    }
  },
  {
    "traceId": "47f9e42180743ba8",
    "id": "47f9e42180743ba8",
    "kind": "SERVER",
    "name": "get /",
    "timestamp": 1552842670001342,
    "duration": 99940,
    "localEndpoint": {
      "serviceName": "async-span",
      "ipv4": "10.238.10.120"
    },
    "tags": {
      "http.method": "GET",
      "http.path": "/",
      "mvc.controller.class": "Endpoint",
      "mvc.controller.method": "test"
    }
  }
]