Update to OTLP 1.1, regenerate protos and pdata (#9588)

**Description:** Updates to OTLP 1.1, published in January 2024. Updates
the `otel/build-protobuf` Docker image to the current release label.

User-visible protocol changes: Adds Span flags and SpanLink flags.

**Link to tracking Issue:** 
Fixes #9587
Fixes #9550 

**Testing:** `make test`

**Documentation:** Could not find any documentation on this process,
added some in CONTRIBUTING.md.

Author: jmacd

.chloggen/update-otlp.yaml

@@ -0,0 +1,6 @@
+change_type: enhancement
+component: pdata
+note: Update to OTLP v1.1.0
+issues: [9587]
+subtext: Introduces Span and SpanLink flags.
+change_logs: [user]

CONTRIBUTING.md

@@ -661,6 +661,19 @@ target would result in unacceptable latency in the local development loop.
 The default repo-level target (i.e. running `make` at the root of the repo) should meaningfully validate the entire repo. This should include
 running the default common target for each module as well as additional repo-level targets.
 
+## How to update the OTLP protocol version
+
+When a new OTLP version is published, the following steps are required to update this code base:
+
+1. Edit the top-level Makefile's `OPENTELEMETRY_PROTO_VERSION` variable
+2. Run `make genproto` 
+3. Inspect modifications to the generated code in `pdata/internal/data/protogen`
+4. When new fields are added in the protocol, make corresponding changes in `pdata/internal/cmd/pdatagen/internal`
+5. Run `make genpdata` 
+6. Inspect modifications to the generated code in `pdata/*`
+7. Run `make genproto-cleanup`, to remove temporary files
+8. Update the supported OTLP version in [README.md](./README.md).
+
 ## Exceptions
 
 While the rules in this and other documents in this repository is what we strive to follow, we acknowledge that rules may be

Makefile

@@ -156,8 +156,8 @@ ocb:
 # The source directory for OTLP ProtoBufs.
 OPENTELEMETRY_PROTO_SRC_DIR=pdata/internal/opentelemetry-proto
 
-# The SHA matching the current version of the proto to use
-OPENTELEMETRY_PROTO_VERSION=v1.0.0
+# The branch matching the current version of the proto to use
+OPENTELEMETRY_PROTO_VERSION=v1.1.0
 
 # Find all .proto files.
 OPENTELEMETRY_PROTO_FILES := $(subst $(OPENTELEMETRY_PROTO_SRC_DIR)/,,$(wildcard $(OPENTELEMETRY_PROTO_SRC_DIR)/opentelemetry/proto/*/v1/*.proto $(OPENTELEMETRY_PROTO_SRC_DIR)/opentelemetry/proto/collector/*/v1/*.proto))
@@ -171,7 +171,7 @@ PROTO_PACKAGE=go.opentelemetry.io/collector/$(PROTO_TARGET_GEN_DIR)
 # Intermediate directory used during generation.
 PROTO_INTERMEDIATE_DIR=pdata/internal/.patched-otlp-proto
 
-DOCKER_PROTOBUF ?= otel/build-protobuf:0.9.0
+DOCKER_PROTOBUF ?= otel/build-protobuf:0.23.0
 PROTOC := docker run --rm -u ${shell id -u} -v${PWD}:${PWD} -w${PWD}/$(PROTO_INTERMEDIATE_DIR) ${DOCKER_PROTOBUF} --proto_path=${PWD}
 PROTO_INCLUDES := -I/usr/include/github.com/gogo/protobuf -I./
 

README.md

@@ -59,6 +59,13 @@ Objectives:
 - Extensible: Customizable without touching the core code.
 - Unified: Single codebase, deployable as an agent or collector with support for traces, metrics and logs.
 
+## Supported OTLP version
+
+This code base is currently built against using OTLP protocol v1.1.0,
+considered Stable. [See the OpenTelemetry Protocol Stability
+definition
+here.](https://github.com/open-telemetry/opentelemetry-proto?tab=readme-ov-file#stability-definition)
+
 ## Stability levels
 
 The collector components and implementation are in different stages of stability, and usually split between

pdata/internal/cmd/pdatagen/internal/ptrace_package.go

@@ -83,6 +83,13 @@ var spanSlice = &sliceOfPtrs{
 	element:    span,
 }
 
+var flagsField = &primitiveField{
+	fieldName:  "Flags",
+	returnType: "uint32",
+	defaultVal: `uint32(0)`,
+	testVal:    `uint32(0xf)`,
+}
+
 var span = &messageValueStruct{
 	structName: "Span",
 	description: "// Span represents a single operation within a trace.\n" +
@@ -94,6 +101,7 @@ var span = &messageValueStruct{
 		traceStateField,
 		parentSpanIDField,
 		nameField,
+		flagsField,
 		&primitiveTypedField{
 			fieldName: "Kind",
 			returnType: &primitiveType{
@@ -167,6 +175,7 @@ var spanLink = &messageValueStruct{
 		traceIDField,
 		spanIDField,
 		traceStateField,
+		flagsField,
 		attributes,
 		droppedAttributesCount,
 	},