Spans get merged when using Zipkin + Akka remote

[ivantopo]

As reported in the mailing list:

Using the Kamon-ore 1.1.2, Kamon-zipkin 1.0.0 I'm investigating an issue we are having with Kamon tracing and Zipkin;

Following the recommended documentation we have set

kamon.trace.join-remote-parents-with-same-span-id = yes

in our configuration since we are using Zipkin.

But it seems that multiple servers are annotating / reusing the same spanId now in resulting in strange unwanted behaviour and having the following span in Zipkin.

Here is a JSON data snapshot of it:

{
    "traceId": "67bbe400678e7434",
    "id": "36d7ccc1701692da",
    "name": "serviceactor: request",
    "parentId": "461c6abaafca62c2",
    "timestamp": 1530693333239282,
    "duration": 92,
    "annotations": [
      {
        "timestamp": 1530693333235463,
        "value": "akka.actor.dequeued",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.15.2"
        }
      },
      {
        "timestamp": 1530693333237837,
        "value": "akka.actor.dequeued",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.7.4"
        }
      },
      {
        "timestamp": 1530693333239317,
        "value": "akka.actor.dequeued",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.16.6"
        }
      }
    ],
    "binaryAnnotations": [
      {
        "key": "akka.actor.class",
        "value": "my.ServiceActor",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.15.2"
        }
      },
      {
        "key": "akka.actor.class",
        "value": "my.ShardingActor",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.7.4"
        }
      },
      {
        "key": "akka.actor.class",
        "value": "my.ShardingActor",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.16.6"
        }
      },
      {
        "key": "akka.actor.message-class",
        "value": "Request",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.15.2"
        }
      },
      {
        "key": "akka.actor.message-class",
        "value": "Select",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.7.4"
        }
      },
      {
        "key": "akka.actor.message-class",
        "value": "Receive",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.16.6"
        }
      },
      {
        "key": "akka.actor.path",
        "value": "application/user/router",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.15.2"
        }
      },
      {
        "key": "akka.actor.path",
        "value": "application/system/sharding/X/28/DsUCvnNOMOOYUiRQuQqcAw",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.7.4"
        }
      },
      {
        "key": "akka.actor.path",
        "value": "application/system/sharding/X/35/2l8k0lT2MFmfLwfLf-mrMQ",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.16.6"
        }
      },
      {
        "key": "akka.system",
        "value": "application",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.15.2"
        }
      },
      {
        "key": "akka.system",
        "value": "application",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.7.4"
        }
      },
      {
        "key": "akka.system",
        "value": "application",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.16.6"
        }
      },
      {
        "key": "component",
        "value": "akka.actor",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.15.2"
        }
      },
      {
        "key": "component",
        "value": "akka.actor",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.7.4"
        }
      },
      {
        "key": "component",
        "value": "akka.actor",
        "endpoint": {
          "serviceName": "api",
          "ipv4": "172.16.16.6"
        }
      }
    ]
  }