[extension/encoding/googlecloudlogentryencoding] accept short ALPN protocol tokens

handleHTTPRequestField required exactly one "/" in the protocol string,
rejecting tokens like "h2" that Google Cloud Load Balancers started using
for HTTP/2 in late 2024.  This silently dropped affected log entries.

Relax the check: if the protocol string contains no "/", store it as-is
in network.protocol.name and omit network.protocol.version. If a "/"
is present the existing validation (both sides must be non-empty) still
applies.

Fixes #45214

Signed-off-by: alliasgher <alliasgher123@gmail.com>

Author: alliasgher

.chloggen/gclog-encoding-h2-protocol.yaml

@@ -0,0 +1,5 @@
+change_type: bug_fix
+component: extension/encoding/googlecloudlogentryencoding
+note: "Accept short ALPN protocol tokens (e.g. `h2`, `h3`) in `httpRequest.protocol` that do not contain a `/`; previously any protocol string without a slash was rejected with an error, causing log entries from Google Cloud Load Balancers that switched to reporting `h2` for HTTP/2 to be silently dropped."
+issues: [45214]
+change_logs: [user]

extension/encoding/googlecloudlogentryencodingextension/log_entry.go

@@ -232,21 +232,26 @@ func handleHTTPRequestField(attributes pcommon.Map, req *httpRequest) error {
 	}
 
 	if req.Protocol != "" {
-		if strings.Count(req.Protocol, "/") != 1 {
+		if strings.Count(req.Protocol, "/") > 1 {
 			return fmt.Errorf(
-				`invalid protocol %q: expected exactly one "/" (format "<name>/<version>", e.g. "HTTP/1.1")`,
+				`invalid protocol %q: expected at most one "/" (format "<name>/<version>", e.g. "HTTP/1.1", or a short token like "h2")`,
 				req.Protocol,
 			)
 		}
-		name, version, found := strings.Cut(req.Protocol, "/")
-		if !found || name == "" || version == "" {
-			return fmt.Errorf(
-				`invalid protocol %q: name or version is missing (expected format "<name>/<version>", e.g. "HTTP/1.1")`,
-				req.Protocol,
-			)
+		if name, version, hasSlash := strings.Cut(req.Protocol, "/"); hasSlash {
+			if name == "" || version == "" {
+				return fmt.Errorf(
+					`invalid protocol %q: name or version is missing (expected format "<name>/<version>", e.g. "HTTP/1.1")`,
+					req.Protocol,
+				)
+			}
+			attributes.PutStr(string(conventions.NetworkProtocolNameKey), strings.ToLower(name))
+			attributes.PutStr(string(conventions.NetworkProtocolVersionKey), version)
+		} else {
+			// Short ALPN token with no version component (e.g. "h2", "h3", "h2c").
+			// Store the full token as the protocol name; no version attribute is set.
+			attributes.PutStr(string(conventions.NetworkProtocolNameKey), strings.ToLower(req.Protocol))
 		}
-		attributes.PutStr(string(conventions.NetworkProtocolNameKey), strings.ToLower(name))
-		attributes.PutStr(string(conventions.NetworkProtocolVersionKey), version)
 	}
 
 	shared.PutInt(string(conventions.HTTPResponseStatusCodeKey), req.Status, attributes)

extension/encoding/googlecloudlogentryencodingextension/log_entry_test.go

@@ -112,11 +112,31 @@ func TestHandleHTTPRequestField(t *testing.T) {
 			expectsErr: "failed to parse request url",
 		},
 		{
-			name: "invalid protocol",
+			// Short ALPN token — accepted as protocol name without version
+			// (regression test for https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/45214)
+			name: "h2 protocol (no slash)",
 			request: &httpRequest{
-				Protocol: "invalid",
+				Protocol: "h2",
 			},
-			expectsErr: `expected exactly one "/"`,
+			expectsAttributes: map[string]any{
+				"network.protocol.name": "h2",
+			},
+		},
+		{
+			name: "h3 protocol (no slash)",
+			request: &httpRequest{
+				Protocol: "h3",
+			},
+			expectsAttributes: map[string]any{
+				"network.protocol.name": "h3",
+			},
+		},
+		{
+			name: "invalid protocol — too many slashes",
+			request: &httpRequest{
+				Protocol: "a/b/c",
+			},
+			expectsErr: `at most one "/"`,
 		},
 		{
 			name: "invalid protocol 2",