Fix apache#1017 Do not hardcode the TransformerFactory implementation…

… irreversibly

extensions-support/xalan/deployment/src/main/java/org/apache/camel/quarkus/support/xalan/deployment/CamelXalanBuildTimeConfig.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.quarkus.support.xalan.deployment;
+
+import java.util.Optional;
+
+import io.quarkus.runtime.annotations.ConfigItem;
+import io.quarkus.runtime.annotations.ConfigPhase;
+import io.quarkus.runtime.annotations.ConfigRoot;
+
+@ConfigRoot(name = "camel.xalan", phase = ConfigPhase.BUILD_TIME)
+public class CamelXalanBuildTimeConfig {
+
+    /**
+     * A fully qualified class name to set as the {@code javax.xml.transform.TransformerFactory} system property early
+     * at the application startup.
+     * <p>
+     * The system property effectively overrides any service providers defined in
+     * {@code META-INF/services/javax.xml.transform.TransformerFactory} files available in the class path. If the option
+     * is not present in your {@code application.properties}, the default value is used and the service providers are
+     * overridden anyway. To avoid overriding the service providers, set it to an empty value in
+     * {@code application.properties}:
+     * 
+     * <pre>
+     * quarkus.camel.xalan.transformer-factory =
+     * </pre>
+     * <p>
+     * Note that any custom transformer factory you pass will only work in native mode if all necessary classes are
+     * registered for reflection and all necessary resources are included in the native image. This may already be the
+     * case for {@code com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl} if you depend on
+     * {@code io.quarkus:quarkus-jaxb} or {@code org.apache.xalan.xsltc.trax.TransformerFactoryImpl} if you depend on
+     * {@code org.apache.camel.quarkus:camel-quarkus-support-xalan}.
+     */
+    @ConfigItem(defaultValue = "org.apache.camel.quarkus.support.xalan.XalanTransformerFactory")
+    public Optional<String> transformerFactory;
+}

extensions-support/xalan/deployment/src/main/java/org/apache/camel/quarkus/support/xalan/deployment/XalanNativeImageProcessor.java

@@ -19,10 +19,13 @@
 import java.util.Arrays;
 import java.util.List;
 
+import io.quarkus.deployment.annotations.BuildProducer;
 import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.builditem.SystemPropertyBuildItem;
 import io.quarkus.deployment.builditem.nativeimage.NativeImageResourceBuildItem;
 import io.quarkus.deployment.builditem.nativeimage.NativeImageResourceBundleBuildItem;
 import io.quarkus.deployment.builditem.nativeimage.ReflectiveClassBuildItem;
+import io.quarkus.deployment.builditem.nativeimage.ServiceProviderBuildItem;
 
 class XalanNativeImageProcessor {
     @BuildStep
@@ -52,4 +55,29 @@ List<NativeImageResourceBuildItem> resources() {
         return Arrays.asList(
                 new NativeImageResourceBuildItem("org/apache/xml/serializer/output_xml.properties"));
     }
+
+    @BuildStep
+    void installTransformerFactory(
+            CamelXalanBuildTimeConfig config,
+            BuildProducer<SystemPropertyBuildItem> properties,
+            BuildProducer<ServiceProviderBuildItem> serviceProviders,
+            BuildProducer<NativeImageResourceBuildItem> nativeResources) {
+
+        config.transformerFactory
+                .ifPresent(val -> properties.produce(
+                        /*
+                         * If we do not do this, the service provider defined in xalan.jar's
+                         * META-INF/services/javax.xml.transform.TransformerFactory
+                         * wins over our factory on Java 11+ native
+                         * I any case, the user has an option to pass his preferred factory instead of ours
+                         */
+                        new SystemPropertyBuildItem("javax.xml.transform.TransformerFactory", val)));
+
+        serviceProviders.produce(
+                new ServiceProviderBuildItem("javax.xml.transform.TransformerFactory",
+                        "org.apache.camel.quarkus.support.xalan.XalanTransformerFactory"));
+
+        nativeResources.produce(new NativeImageResourceBuildItem("META-INF/services/javax.xml.transform.TransformerFactory"));
+    }
+
 }

extensions-support/xalan/runtime/src/main/resources/META-INF/services/javax.xml.transform.TransformerFactory

@@ -0,0 +1 @@
+org.apache.camel.quarkus.support.xalan.XalanTransformerFactory