Allow transforming the DB2 JDBC driver to Jakarta APIs during Augmentation

extensions/jdbc/jdbc-db2/deployment/pom.xml

@@ -48,6 +48,11 @@
             <artifactId>assertj-core</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.eclipse.transformer</groupId>
+            <artifactId>org.eclipse.transformer</artifactId>
+            <version>0.5.0</version>
+        </dependency>
     </dependencies>
 
     <build>

extensions/jdbc/jdbc-db2/deployment/src/main/java/io/quarkus/jdbc/db2/deployment/JakartaEnablement.java

@@ -0,0 +1,82 @@
+package io.quarkus.jdbc.db2.deployment;
+
+import java.nio.ByteBuffer;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.transformer.action.ActionContext;
+import org.eclipse.transformer.action.ByteData;
+import org.eclipse.transformer.action.impl.ActionContextImpl;
+import org.eclipse.transformer.action.impl.ByteDataImpl;
+import org.eclipse.transformer.action.impl.ClassActionImpl;
+import org.eclipse.transformer.action.impl.SelectionRuleImpl;
+import org.eclipse.transformer.action.impl.SignatureRuleImpl;
+import org.eclipse.transformer.util.FileUtils;
+import org.objectweb.asm.ClassReader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.quarkus.bootstrap.classloading.QuarkusClassLoader;
+import io.quarkus.deployment.annotations.BuildProducer;
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.builditem.BytecodeTransformerBuildItem;
+
+/**
+ * The DB2 driver is compiled using references to classes in the javax.transaction
+ * package; we need to transform these to fix compatibility with jakarta.transaction.
+ * We do this by leveraging the Eclipse Transformer project during Augmentation, so
+ * that end users don't need to bother.
+ */
+public class JakartaEnablement {
+
+    private static final List<String> CLASSES_NEEDING_TRANSFORMATION = List.of(
+            "com.ibm.db2.jcc.t2zos.ab",
+            "com.ibm.db2.jcc.t2zos.T2zosConnection",
+            "com.ibm.db2.jcc.t2zos.T2zosConfiguration");
+
+    @BuildStep
+    void transformToJakarta(BuildProducer<BytecodeTransformerBuildItem> transformers) {
+        if (QuarkusClassLoader.isClassPresentAtRuntime("jakarta.transaction.Transaction")) {
+            JakartaTransformer tr = new JakartaTransformer();
+            for (String classname : CLASSES_NEEDING_TRANSFORMATION) {
+                final BytecodeTransformerBuildItem item = new BytecodeTransformerBuildItem.Builder()
+                        .setCacheable(true)
+                        .setContinueOnFailure(false)
+                        .setClassToTransform(classname)
+                        .setClassReaderOptions(ClassReader.SKIP_DEBUG)
+                        .setInputTransformer(tr::transform)
+                        .build();
+                transformers.produce(item);
+            }
+        }
+    }
+
+    private static class JakartaTransformer {
+
+        private final Logger logger;
+        private final ActionContext ctx;
+
+        JakartaTransformer() {
+            logger = LoggerFactory.getLogger("JakartaTransformer");
+            Map<String, String> renames = new HashMap<>();
+            //N.B. we enable only this transformation, not the full set of capabilities of Eclipse Transformer;
+            //this might need tailoring if the same idea gets applied to a different context.
+            renames.put("javax.transaction", "jakarta.transaction");
+            ctx = new ActionContextImpl(logger,
+                    new SelectionRuleImpl(logger, Collections.emptyMap(), Collections.emptyMap()),
+                    new SignatureRuleImpl(logger, renames, null, null, null, null, null, Collections.emptyMap()));
+        }
+
+        byte[] transform(final String name, final byte[] bytes) {
+            logger.info("Jakarta EE compatibility enhancer for Quarkus: transforming " + name);
+            final ClassActionImpl classTransformer = new ClassActionImpl(ctx);
+            final ByteBuffer input = ByteBuffer.wrap(bytes);
+            final ByteData inputData = new ByteDataImpl(name, input, FileUtils.DEFAULT_CHARSET);
+            final ByteData outputData = classTransformer.apply(inputData);
+            return outputData.buffer().array();
+        }
+    }
+
+}