Bazel build for Zipkin (#916)

Author: lalitb

exporters/zipkin/BUILD

@@ -0,0 +1,44 @@
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "zipkin_recordable",
+    srcs = [
+        "src/recordable.cc",
+    ],
+    hdrs = [
+        "include/opentelemetry/exporters/zipkin/recordable.h",
+    ],
+    strip_include_prefix = "include",
+    deps = [
+        "//sdk/src/resource",
+        "//sdk/src/trace",
+        "@github_nlohmann_json//:json",
+    ],
+)
+
+cc_library(
+    name = "zipkin_exporter",
+    srcs = [
+        "src/zipkin_exporter.cc",
+    ],
+    hdrs = [
+        "include/opentelemetry/exporters/zipkin/zipkin_exporter.h",
+    ],
+    copts = [
+        "-DCURL_STATICLIB",
+    ],
+    strip_include_prefix = "include",
+    deps = [
+        ":zipkin_recordable",
+        "//ext/src/http/client/curl:http_client_curl",
+    ],
+)
+
+cc_test(
+    name = "zipkin_recordable_test",
+    srcs = ["test/zipkin_recordable_test.cc"],
+    deps = [
+        ":zipkin_recordable",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

exporters/zipkin/src/zipkin_exporter.cc

@@ -62,8 +62,8 @@ sdk::common::ExportResult ZipkinExporter::Export(
   auto body_s = json_spans.dump();
   http_client::Body body_v(body_s.begin(), body_s.end());
   auto result = http_client_->Post(url_parser_.url_, body_v);
-  if (result && result.GetResponse().GetStatusCode() == 200 ||
-      result.GetResponse().GetStatusCode() == 202)
+  if (result &&
+      (result.GetResponse().GetStatusCode() == 200 || result.GetResponse().GetStatusCode() == 202))
   {
     return sdk::common::ExportResult::kSuccess;
   }

exporters/zipkin/test/zipkin_recordable_test.cc

@@ -144,7 +144,6 @@ TEST(ZipkinSpanRecordable, AddEventDefault)
 TEST(ZipkinSpanRecordable, AddEventWithAttributes)
 {
   opentelemetry::exporter::zipkin::Recordable rec;
-  nostd::string_view name = "Test Event";
 
   std::chrono::system_clock::time_point event_time = std::chrono::system_clock::now();
   opentelemetry::common::SystemTimestamp event_timestamp(event_time);