add CHANGELOG and enhance release notes

Author: ezhang6811

.github/workflows/release-build.yml

@@ -412,20 +412,39 @@ jobs:
           OTEL_INSTRUMENTATION_VERSION=$(grep "val otelVersion" dependencyManagement/build.gradle.kts | sed 's/.*= "\([^"]*\)".*/\1/')
           OTEL_CONTRIB_VERSION=$(grep "io.opentelemetry.contrib:opentelemetry-aws-xray" dependencyManagement/build.gradle.kts | sed 's/.*:\([^"]*\)".*/\1/')
 
+          # Extract CHANGELOG entries for this version
+          CHANGELOG_ENTRIES=$(python3 -c "
+          import re
+          with open('CHANGELOG.md', 'r') as f:
+              content = f.read()
+          version_pattern = r'## v${{ github.event.inputs.version }}.*?\n(.*?)(?=\n## |\Z)'
+          version_match = re.search(version_pattern, content, re.DOTALL)
+          if version_match:
+              entries = version_match.group(1).strip()
+              if entries:
+                  print(entries)
+          ")
+
           # Create release notes
           cat > release_notes.md << EOF
-          This release contains updates of the following upstream components:
+          $(if [ -n "$CHANGELOG_ENTRIES" ]; then echo "## What's Changed"; echo "$CHANGELOG_ENTRIES"; echo ""; fi)
+
+          ## Upstream Components
 
-          OpenTelemetry Java Contrib - $OTEL_CONTRIB_VERSION
-          Opentelemetry Instrumentation for Java - $OTEL_INSTRUMENTATION_VERSION
+          - \`OpenTelemetry Java Contrib\` - $OTEL_CONTRIB_VERSION
+          - \`Opentelemetry Instrumentation for Java\` - $OTEL_INSTRUMENTATION_VERSION
 
-          This release also publishes to public ECR and Maven Central.
+          ## Release Artifacts
+
+          This release publishes to public ECR and Maven Central.
           * See ADOT Java auto-instrumentation Docker image v${{ github.event.inputs.version }} in our public ECR repository:
           https://gallery.ecr.aws/aws-observability/adot-autoinstrumentation-java
           * See version ${{ github.event.inputs.version }} in our Maven Central repository:
           https://central.sonatype.com/artifact/software.amazon.opentelemetry/aws-opentelemetry-agent
 
-          This release also includes the AWS OpenTelemetry Lambda Layer for Java version ${{ github.event.inputs.version }}-$(echo $GITHUB_SHA | cut -c1-7).
+          ## Lambda Layer
+
+          This release includes the AWS OpenTelemetry Lambda Layer for Java version ${{ github.event.inputs.version }}-$(echo $GITHUB_SHA | cut -c1-7).
 
           Lambda Layer ARNs:
           ${{ needs.generate-lambda-release-note.outputs.layer-note }}