try

Author: trask

smoke-tests/images/quarkus/build.gradle.kts

@@ -26,6 +26,14 @@ val targetJDK = project.findProperty("targetJDK") ?: "17"
 val tag = findProperty("tag")
   ?: DateTimeFormatter.ofPattern("yyyyMMdd.HHmmSS").format(LocalDateTime.now())
 
+java {
+  // this is needed to avoid jib failing with
+  // "Your project is using Java 21 but the base image is for Java 17"
+  // (it seems the jib plugins does not understand toolchains yet)
+  sourceCompatibility = JavaVersion.VERSION_17
+  targetCompatibility = JavaVersion.VERSION_17
+}
+
 jib {
   from.image = "eclipse-temurin:$targetJDK"
   to.image = "ghcr.io/open-telemetry/opentelemetry-java-instrumentation/smoke-test-quarkus:jdk$targetJDK-$tag"