Fix sporadic CI failures by excluding Netty buffer classes from JaCoCo

- Exclude io/netty/buffer/*Event* classes from JaCoCo instrumentation
- This prevents instrumentation conflicts that cause sporadic test failures
- These classes are already instrumented by OpenTelemetry agents and attempting
  to instrument them again with JaCoCo causes IllegalClassFormatException
- Affects tests like SimpleHttpClientTest goodCert and others using Armeria
  that depend on Netty buffer management

Author: trask

.github/workflows/stress-test-the-build.yml

@@ -14,13 +14,13 @@ jobs:
     name: Test
     runs-on: ${{ matrix.os }}
     strategy:
-      fail-fast: false
       matrix:
         os:
           - windows-latest
         test-java-version:
           - 8
         run-number: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+      fail-fast: false
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 

buildSrc/src/main/kotlin/otel.java-conventions.gradle.kts

@@ -1,5 +1,6 @@
 import io.opentelemetry.gradle.OtelJavaExtension
 import org.gradle.api.tasks.testing.logging.TestExceptionFormat
+import org.gradle.testing.jacoco.tasks.JacocoTaskExtension
 
 plugins {
   `java-library`
@@ -70,6 +71,12 @@ tasks {
       exceptionFormat = TestExceptionFormat.FULL
       showStandardStreams = true
     }
+    
+    // Configure JaCoCo agent to exclude problematic Netty buffer classes that can cause
+    // instrumentation conflicts and sporadic test failures
+    configure<JacocoTaskExtension> {
+      excludes = listOf("**/io/netty/buffer/*Event*")
+    }
   }
 
   withType<Javadoc>().configureEach {