Zipkin Api 1.0

This is recognizes that the formats here are long since stable and we haven't broken compatibility.

Zipkin API 0.2.2

Zipkin Api v0.2.2 adds a convenience file zipkin-jsonv2.proto, allowing protobuf tools to generate json serialization code compatible with our OpenApi spec.

Thanks very much to @dio who helped verify and use this in support of Envoy migrating to our newer data format.

Zipkin API 0.2.1

Zipkin API 0.2.1 fixes the result type of the span reporting endpoint to not imply a google empty type. This simplifies compiler configuration and dependencies needed to use the service.

For example, the following kotlin wire client no longer needs any google library dependencies as the result type is not a google type

    @WireRpc(
      path = "/zipkin.proto3.SpanService/Report",
      requestAdapter = "zipkin2.proto3.ListOfSpans#ADAPTER",
-      responseAdapter = "com.google.protobuf.Empty#ADAPTER"
+      responseAdapter = "zipkin2.proto3.ReportResponse#ADAPTER"
    )
-    suspend fun Report(request: ListOfSpans): Empty
+    suspend fun Report(request: ListOfSpans): ReportResponse
  }

Zipkin Api 0.2.0 introduces a protobuf reporting service

Some users requested a gRPC endpoint in #57.

We've added SpanService.Report, which takes the same message as our POST /api/v2/spans with content type application/x-protobuf. This allows normal protobuf binding as well as gRPC to work without limiting us to features that don't work universally such as streaming.