Go package compliance (#426)

* update to a compliant gopath
* add go import paths to external protos
* update metrics.proto from current prometheus source
* changelog
* changelog
* changelog
* revert metrics.proto update
* changelog

README.md

@@ -31,7 +31,7 @@ root level `generate.go` file.
 
 ## upgrading to v0.12.0 (solo-kit with go.mod)
 
-As of go 1.11, go began introducing support for go modules, it's dependency management system.
+As of go 1.11, go began introducing support for go modules, its dependency management system.
 As of solo-kit 0.12.0 we will officially support running solo-kit with go.mod outside of the GOPATH.
 
 This change has been a lot time coming, but it also means a few changes to solo-kit.

api/external/metrics.proto

@@ -21,7 +21,7 @@ import "extproto/ext.proto";
 option (extproto.hash_all) = true;
 option (extproto.equal_all) = true;
 
-option go_package = "metricsproto";
+option go_package = "github.com/prometheus/client_model/go;io_prometheus_client";
 
 message LabelPair {
   optional string name  = 1;

api/external/trace.proto

@@ -28,7 +28,7 @@ option java_multiple_files = true;
 option java_package = "io.opencensus.proto.trace";
 option java_outer_classname = "TraceProto";
 
-option go_package = "traceproto";
+option go_package = "github.com/census-instrumentation/opencensus-proto/gen-go/trace/v1";
 
 // A span represents a single operation within a trace. Spans can be
 // nested to form a trace tree. Often, a trace contains a root span
@@ -355,4 +355,4 @@ message TruncatableString {
   // The number of bytes removed from the original string. If this
   // value is 0, then the string was not shortened.
   int32 truncated_byte_count = 2;
-}
+}

changelog/v0.21.0/gopackage-compliance.yaml

@@ -0,0 +1,4 @@
+changelog:
+  - type: BREAKING_CHANGE
+    description: Update `go_package` field of external protos to comply with latest `protoc-gen-go` requirements.
+    issueLink: https://github.com/solo-io/solo-kit/issues/427