fix: Enforce ByteCode 1.8 on some jetty projects

Author: bric3

dd-java-agent/instrumentation/jetty/jetty-client/jetty-client-10.0/build.gradle

@@ -28,7 +28,7 @@ addTestSuiteForDir('jetty11Test', 'test')
 addTestSuiteForDir('jetty10LatestDepTest', 'test')
 
 tasks.named("compileMain_java11Java", JavaCompile) {
-  configureCompiler(it, 11, JavaVersion.VERSION_11)
+  configureCompiler(it, 11, JavaVersion.VERSION_1_8)
 }
 
 dependencies {

dd-java-agent/instrumentation/jetty/jetty-server/jetty-server-11.0/build.gradle

@@ -17,6 +17,10 @@ apply plugin: "idea"
 addTestSuiteForDir('latestDepTest', 'test')
 addTestSuiteForDir('latestDepForkedTest', 'test')
 
+tasks.named("compileMain_java11Java") {
+  configureCompiler(it, 11, JavaVersion.VERSION_1_8)
+}
+
 tasks.withType(GroovyCompile).configureEach {
   javaLauncher = getJavaLauncherFor(11)
 }