Native image - ClassNotFoundException: org.conscrypt.BufferAllocator
**Describe the bug**

When upgrading from Quarkus 0.19.0 to 0.23.1 (GraalVM 19.0.2 to 19.2.0.1) I'm getting this error at native-image compilation:

```
[2019-09-26T17:55:00.105Z] [INFO] [io.quarkus.creator.phase.nativeimage.NativeImagePhase] Running Quarkus native-image plugin on OpenJDK 64-Bit GraalVM CE 19.2.0.1
[2019-09-26T17:55:00.105Z] [INFO] [io.quarkus.creator.phase.nativeimage.NativeImagePhase] /opt/graalvm/bin/native-image -J-Dsun.nio.ch.maxUpdateArraySize=100 -J-Dio.netty.noUnsafe=true -J-Dvertx.logger-delegate-factory-class-name=io.quarkus.vertx.core.runtime.VertxLogDelegateFactory -J-Dio.netty.leakDetection.level=DISABLED -J-Djava.util.logging.manager=org.jboss.logmanager.LogManager -J-Dcom.sun.xml.bind.v2.bytecode.ClassTailor.noOptimize=true -J-Dvertx.disableDnsResolver=true --initialize-at-build-time= -H:InitialCollectionPolicy=com.oracle.svm.core.genscavenge.CollectionPolicy$BySpaceAndTime -jar ojf-quarkus-packaging-runner.jar -J-Djava.util.concurrent.ForkJoinPool.common.parallelism=1 -H:FallbackThreshold=0 -H:+ReportUnsupportedElementsAtRuntime -H:+ReportExceptionStackTraces -H:+PrintAnalysisCallTree -H:-AddAllCharsets -H:EnableURLProtocols=http -H:+JNI --no-server -H:-UseServiceLoaderFeature -H:+StackTrace
[2019-09-26T17:55:26.895Z] [quarkus-packaging-runner:1115]    classlist:  23,885.64 ms
[2019-09-26T17:55:26.895Z] [quarkus-packaging-runner:1115]        setup:     520.25 ms
[2019-09-26T17:55:26.895Z] Fatal error: java.lang.NoClassDefFoundError
[2019-09-26T17:55:26.895Z] 	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[2019-09-26T17:55:26.895Z] 	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
[2019-09-26T17:55:26.895Z] 	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
[2019-09-26T17:55:26.895Z] 	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinTask.getThrowableException(ForkJoinTask.java:598)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinTask.get(ForkJoinTask.java:1005)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGenerator.run(NativeImageGenerator.java:461)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGeneratorRunner.buildImage(NativeImageGeneratorRunner.java:310)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGeneratorRunner.build(NativeImageGeneratorRunner.java:448)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGeneratorRunner.main(NativeImageGeneratorRunner.java:113)
[2019-09-26T17:55:26.896Z] Caused by: java.lang.NoClassDefFoundError: org/conscrypt/BufferAllocator
[2019-09-26T17:55:26.896Z] 	at java.lang.Class.getDeclaredMethods0(Native Method)
[2019-09-26T17:55:26.896Z] 	at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
[2019-09-26T17:55:26.896Z] 	at java.lang.Class.getDeclaredMethods(Class.java:1975)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.substitute.AnnotationSubstitutionProcessor.handleDeletedClass(AnnotationSubstitutionProcessor.java:437)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.substitute.AnnotationSubstitutionProcessor.handleClass(AnnotationSubstitutionProcessor.java:270)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.substitute.AnnotationSubstitutionProcessor.init(AnnotationSubstitutionProcessor.java:230)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGenerator.createDeclarativeSubstitutionProcessor(NativeImageGenerator.java:875)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGenerator.setupNativeImage(NativeImageGenerator.java:824)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGenerator.doRun(NativeImageGenerator.java:524)
[2019-09-26T17:55:26.896Z] 	at com.oracle.svm.hosted.NativeImageGenerator.lambda$run$0(NativeImageGenerator.java:444)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinTask$AdaptedRunnableAction.exec(ForkJoinTask.java:1386)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
[2019-09-26T17:55:26.896Z] 	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
[2019-09-26T17:55:26.896Z] Caused by: java.lang.ClassNotFoundException: org.conscrypt.BufferAllocator
[2019-09-26T17:55:26.896Z] 	at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
[2019-09-26T17:55:26.896Z] 	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
[2019-09-26T17:55:26.896Z] 	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
[2019-09-26T17:55:26.896Z] 	... 15 more
[2019-09-26T17:55:26.896Z] Error: Image build request failed with exit status 1
```

I tried to zgrep for conscrypt or org.conscrypt.BufferAllocator in target/lib, but didn't find any references in any jar.

**Expected behavior**

Should compile (was fine on Quarkus 0.19.0 + GraalVM 19.0.2).

**To Reproduce**

I don't have a reproducer I can share, but:
- I'm using the docker image quay.io/quarkus/centos-quarkus-maven:19.2.0.1 to build.
- My application uses the following extensions: quarkus-undertow, quarkus-spring-di, quarkus-resteasy, and a custom one with a servlet and some Arc beans.

**Environment (please complete the following information):**
 - Output of `uname -a` or `ver`:  `Linux 8e5961cd5b12 3.10.0-693.5.2.el7.x86_64 #1 SMP Fri Oct 13 10:46:25 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux`
 - Output of `java -version`:  `openjdk version "1.8.0_222"`
`OpenJDK Runtime Environment (build 1.8.0_222-20190711120915.buildslave.jdk8u-src-tar--b08)
OpenJDK 64-Bit GraalVM CE 19.2.0.1 (build 25.222-b08-jvmci-19.2-b02, mixed mode)`
 - GraalVM version (if different from Java): `GraalVM CE 19.2.0.1`
 - Quarkus version or git rev: 0.23.1

**Additional context**

I've only seen the same error mentioned in https://github.com/apache/camel-quarkus/issues/132
diff --git a/extensions/netty/runtime/src/main/java/io/quarkus/netty/runtime/graal/NettySubstitutions.java b/extensions/netty/runtime/src/main/java/io/quarkus/netty/runtime/graal/NettySubstitutions.java
index ab2bb428f41..da0521e7f6e 100644
--- a/extensions/netty/runtime/src/main/java/io/quarkus/netty/runtime/graal/NettySubstitutions.java
+++ b/extensions/netty/runtime/src/main/java/io/quarkus/netty/runtime/graal/NettySubstitutions.java
@@ -12,11 +12,11 @@
 import javax.net.ssl.TrustManagerFactory;
 
 import com.oracle.svm.core.annotate.Alias;
-import com.oracle.svm.core.annotate.Delete;
 import com.oracle.svm.core.annotate.RecomputeFieldValue;
 import com.oracle.svm.core.annotate.Substitute;
 import com.oracle.svm.core.annotate.TargetClass;
 import com.oracle.svm.core.jdk.JDK11OrLater;
+import com.oracle.svm.core.jdk.JDK8OrEarlier;
 
 import io.netty.bootstrap.AbstractBootstrapConfig;
 import io.netty.bootstrap.ChannelFactory;
@@ -92,11 +92,6 @@ final class Target_io_netty_handler_ssl_SslHandler$SslEngineType {
     }
 }
 
-@Delete
-@TargetClass(className = "io.netty.handler.ssl.ConscryptAlpnSslEngine")
-final class Target_io_netty_handler_ssl_ConscryptAlpnSslEngine {
-}
-
 @TargetClass(className = "io.netty.handler.ssl.JdkAlpnApplicationProtocolNegotiator$AlpnWrapper", onlyWith = JDK11OrLater.class)
 final class Target_io_netty_handler_ssl_JdkAlpnApplicationProtocolNegotiator_AlpnWrapper {
     @Substitute
@@ -107,6 +102,43 @@ public SSLEngine wrapSslEngine(SSLEngine engine, ByteBufAllocator alloc,
 
 }
 
+@TargetClass(className = "io.netty.handler.ssl.JdkAlpnApplicationProtocolNegotiator$AlpnWrapper", onlyWith = JDK8OrEarlier.class)
+final class Target_io_netty_handler_ssl_JdkAlpnApplicationProtocolNegotiator_AlpnWrapperJava8 {
+    @Substitute
+    public SSLEngine wrapSslEngine(SSLEngine engine, ByteBufAllocator alloc,
+            JdkApplicationProtocolNegotiator applicationNegotiator, boolean isServer) {
+        if (Target_io_netty_handler_ssl_JettyAlpnSslEngine.isAvailable()) {
+            return isServer
+                    ? (SSLEngine) (Object) Target_io_netty_handler_ssl_JettyAlpnSslEngine.newServerEngine(engine,
+                            applicationNegotiator)
+                    : (SSLEngine) (Object) Target_io_netty_handler_ssl_JettyAlpnSslEngine.newClientEngine(engine,
+                            applicationNegotiator);
+        }
+        throw new RuntimeException("Unable to wrap SSLEngine of type " + engine.getClass().getName());
+    }
+
+}
+
+@TargetClass(className = "io.netty.handler.ssl.JettyAlpnSslEngine", onlyWith = JDK8OrEarlier.class)
+final class Target_io_netty_handler_ssl_JettyAlpnSslEngine {
+    @Alias
+    static boolean isAvailable() {
+        return false;
+    }
+
+    @Alias
+    static Target_io_netty_handler_ssl_JettyAlpnSslEngine newClientEngine(SSLEngine engine,
+            JdkApplicationProtocolNegotiator applicationNegotiator) {
+        return null;
+    }
+
+    @Alias
+    static Target_io_netty_handler_ssl_JettyAlpnSslEngine newServerEngine(SSLEngine engine,
+            JdkApplicationProtocolNegotiator applicationNegotiator) {
+        return null;
+    }
+}
+
 @TargetClass(className = "io.netty.handler.ssl.Java9SslEngine", onlyWith = JDK11OrLater.class)
 final class Target_io_netty_handler_ssl_Java9SslEngine {
     @Alias
['extensions/netty/runtime/src/main/java/io/quarkus/netty/runtime/graal/NettySubstitutions.java']