fix(otlptrace,otlpmetric): remove endpoint URL path cleaning (#6710)

When setting an explicit OTLP traces endpoint URL (via
`otlptracehttp.WithEndpointURL` or the
`OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` environment variable), any given
trailing slash is stripped. This makes it impossible to export traces to
an endpoint requiring a trailing slash. It also conflicts with [the
spec](https://opentelemetry.io/docs/specs/otel/protocol/exporter/#endpoint-urls-for-otlphttp):

> For the per-signal variables (OTEL_EXPORTER_OTLP_\<signal\>_ENDPOINT),
the URL MUST be used as-is without any modification. The only exception
is that if an URL contains no path part, the root path / MUST be used
(see [Example
2](https://opentelemetry.io/docs/specs/otel/protocol/exporter/#example-2)).

This stripping happens due to [the use of `path.Clean` in
`otlpconfig.cleanPath`](https://github.com/open-telemetry/opentelemetry-go/blob/b4b461d050f1d0f5bda89ddac718180162120606/exporters/otlp/otlptrace/otlptracehttp/internal/otlpconfig/options.go#L97).
From [the `path.Clean` docs](https://pkg.go.dev/path#Clean):

> The returned path ends in a slash only if it is the root "/".

Fixes #6709.

Author: mjq

CHANGELOG.md

@@ -34,6 +34,13 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - The semantic conventions have been upgraded from `v1.26.0` to `v1.34.0` in `go.opentelemetry.io/otel/sdk/trace`. (#6835)
 - The semantic conventions have been upgraded from `v1.26.0` to `v1.34.0` in `go.opentelemetry.io/otel/trace`. (#6836)
 
+### Fixed
+
+- Stop stripping trailing slashes from configured endpoint URL in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc`. (#6710)
+- Stop stripping trailing slashes from configured endpoint URL in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`. (#6710)
+- Stop stripping trailing slashes from configured endpoint URL in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc`. (#6710)
+- Stop stripping trailing slashes from configured endpoint URL in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp`. (#6710)
+
 <!-- Released section -->
 <!-- Don't change this section unless doing release -->
 

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options.go

@@ -105,12 +105,11 @@ func NewHTTPConfig(opts ...HTTPOption) Config {
 	return cfg
 }
 
-// cleanPath returns a path with all spaces trimmed and all redundancies
-// removed. If urlPath is empty or cleaning it results in an empty string,
+// cleanPath returns a path with all spaces trimmed. If urlPath is empty,
 // defaultPath is returned instead.
 func cleanPath(urlPath string, defaultPath string) string {
-	tmp := path.Clean(strings.TrimSpace(urlPath))
-	if tmp == "." {
+	tmp := strings.TrimSpace(urlPath)
+	if tmp == "" || tmp == "." {
 		return defaultPath
 	}
 	if !path.IsAbs(tmp) {

exporters/otlp/otlpmetric/otlpmetricgrpc/internal/oconf/options_test.go

@@ -627,10 +627,10 @@ func TestCleanPath(t *testing.T) {
 		{
 			name: "clean traces path",
 			args: args{
-				urlPath:     "https://env_endpoint",
+				urlPath:     "https://env_endpoint/ ",
 				defaultPath: "DefaultTracesPath",
 			},
-			want: "/https:/env_endpoint",
+			want: "/https://env_endpoint/",
 		},
 		{
 			name: "spaces trimmed",
@@ -639,14 +639,6 @@ func TestCleanPath(t *testing.T) {
 			},
 			want: "/dir",
 		},
-		{
-			name: "clean path empty",
-			args: args{
-				urlPath:     "dir/..",
-				defaultPath: "DefaultTracesPath",
-			},
-			want: "DefaultTracesPath",
-		},
 		{
 			name: "make absolute",
 			args: args{

exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options.go

@@ -92,12 +92,11 @@ func NewHTTPConfig(opts ...HTTPOption) Config {
 	return cfg
 }
 
-// cleanPath returns a path with all spaces trimmed and all redundancies
-// removed. If urlPath is empty or cleaning it results in an empty string,
+// cleanPath returns a path with all spaces trimmed. If urlPath is empty,
 // defaultPath is returned instead.
 func cleanPath(urlPath string, defaultPath string) string {
-	tmp := path.Clean(strings.TrimSpace(urlPath))
-	if tmp == "." {
+	tmp := strings.TrimSpace(urlPath)
+	if tmp == "" || tmp == "." {
 		return defaultPath
 	}
 	if !path.IsAbs(tmp) {

exporters/otlp/otlpmetric/otlpmetrichttp/internal/oconf/options_test.go

@@ -569,10 +569,10 @@ func TestCleanPath(t *testing.T) {
 		{
 			name: "clean traces path",
 			args: args{
-				urlPath:     "https://env_endpoint",
+				urlPath:     "https://env_endpoint/ ",
 				defaultPath: "DefaultTracesPath",
 			},
-			want: "/https:/env_endpoint",
+			want: "/https://env_endpoint/",
 		},
 		{
 			name: "spaces trimmed",
@@ -581,14 +581,6 @@ func TestCleanPath(t *testing.T) {
 			},
 			want: "/dir",
 		},
-		{
-			name: "clean path empty",
-			args: args{
-				urlPath:     "dir/..",
-				defaultPath: "DefaultTracesPath",
-			},
-			want: "DefaultTracesPath",
-		},
 		{
 			name: "make absolute",
 			args: args{