Allow not detecting the extension

We actually have some level of support for building an extension with
Gradle so we need to make it work.
However, at the moment, it's close to impossible to determine the
extension we are in in a Gradle extension.
So we allow not detecting the extension and disable the config doc
generation in this case.

core/processor/src/main/java/io/quarkus/annotation/processor/ExtensionAnnotationProcessor.java

@@ -16,6 +16,7 @@
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
 import javax.tools.Diagnostic;
+import javax.tools.Diagnostic.Kind;
 
 import org.jboss.jdeparser.JDeparser;
 
@@ -38,19 +39,6 @@ public class ExtensionAnnotationProcessor extends AbstractProcessor {
     public synchronized void init(ProcessingEnvironment processingEnv) {
         super.init(processingEnv);
 
-        List<ExtensionProcessor> extensionProcessors = new ArrayList<>();
-        extensionProcessors.add(new ExtensionBuildProcessor());
-
-        boolean skipDocs = Boolean.getBoolean("skipDocs") || Boolean.getBoolean("quickly");
-        boolean generateDoc = !skipDocs && !"false".equals(processingEnv.getOptions().get(Options.GENERATE_DOC));
-
-        // for now, we generate the old config doc by default but we will change this behavior soon
-        if (generateDoc) {
-            extensionProcessors.add(new ConfigDocExtensionProcessor());
-        }
-
-        this.extensionProcessors = Collections.unmodifiableList(extensionProcessors);
-
         utils = new Utils(processingEnv);
 
         boolean useConfigMapping = !Boolean
@@ -65,7 +53,25 @@ public synchronized void init(ProcessingEnvironment processingEnv) {
                     + " config implementation is deprecated. Please migrate to use @ConfigMapping: https://quarkus.io/guides/writing-extensions#configuration");
         }
 
-        for (ExtensionProcessor extensionProcessor : extensionProcessors) {
+        List<ExtensionProcessor> extensionProcessors = new ArrayList<>();
+        extensionProcessors.add(new ExtensionBuildProcessor());
+
+        boolean skipDocs = Boolean.getBoolean("skipDocs") || Boolean.getBoolean("quickly");
+        boolean generateDoc = !skipDocs && !"false".equals(processingEnv.getOptions().get(Options.GENERATE_DOC));
+
+        // for now, we generate the old config doc by default but we will change this behavior soon
+        if (generateDoc) {
+            if (extension.detected()) {
+                extensionProcessors.add(new ConfigDocExtensionProcessor());
+            } else {
+                processingEnv.getMessager().printMessage(Kind.WARNING,
+                        "We could not detect the groupId and artifactId of this module (maybe you are using Gradle to build your extension?). The generation of the configuration documentation has been disabled.");
+            }
+        }
+
+        this.extensionProcessors = Collections.unmodifiableList(extensionProcessors);
+
+        for (ExtensionProcessor extensionProcessor : this.extensionProcessors) {
             extensionProcessor.init(config, utils);
         }
     }

core/processor/src/main/java/io/quarkus/annotation/processor/documentation/config/model/Extension.java

@@ -5,7 +5,11 @@
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
 public record Extension(String groupId, String artifactId, String name,
-        NameSource nameSource) implements Comparable<Extension> {
+        NameSource nameSource, boolean detected) implements Comparable<Extension> {
+
+    public static Extension createNotDetected() {
+        return new Extension("not.detected", "not.detected", "Not detected", NameSource.NONE, false);
+    }
 
     @Override
     public final String toString() {

core/processor/src/main/java/io/quarkus/annotation/processor/util/ExtensionUtil.java

@@ -4,6 +4,8 @@
 import java.util.Map;
 import java.util.Optional;
 
+import javax.annotation.processing.ProcessingEnvironment;
+import javax.tools.Diagnostic.Kind;
 import javax.xml.XMLConstants;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -26,9 +28,11 @@ public final class ExtensionUtil {
     private static final String NAME_COMMON_SUFFIX = " - Common";
     private static final String NAME_INTERNAL_SUFFIX = " - Internal";
 
+    private final ProcessingEnvironment processingEnv;
     private final FilerUtil filerUtil;
 
-    ExtensionUtil(FilerUtil filerUtil) {
+    ExtensionUtil(ProcessingEnvironment processingEnv, FilerUtil filerUtil) {
+        this.processingEnv = processingEnv;
         this.filerUtil = filerUtil;
     }
 
@@ -37,21 +41,25 @@ public final class ExtensionUtil {
      * One option would be to pass it through the annotation processor but it's not exactly ideal.
      */
     public Extension getExtension() {
-        Path pom = filerUtil.getPomPath();
+        Optional<Path> pom = filerUtil.getPomPath();
+
+        if (pom.isEmpty()) {
+            return Extension.createNotDetected();
+        }
 
         Document doc;
 
         try {
             DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
             dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
             DocumentBuilder db = dbf.newDocumentBuilder();
-            doc = db.parse(pom.toFile());
+            doc = db.parse(pom.get().toFile());
             doc.getDocumentElement().normalize();
         } catch (Exception e) {
             throw new IllegalStateException("Unable to parse pom file: " + pom, e);
         }
 
-        return getExtensionFromPom(pom, doc);
+        return getExtensionFromPom(pom.get(), doc);
     }
 
     private Extension getExtensionFromPom(Path pom, Document doc) {
@@ -99,7 +107,8 @@ private Extension getExtensionFromPom(Path pom, Document doc) {
         }
 
         if (groupId == null || groupId.isBlank() || artifactId == null || artifactId.isBlank()) {
-            throw new IllegalStateException("Unable to determine artifact coordinates from: " + pom);
+            processingEnv.getMessager().printMessage(Kind.WARNING, "Unable to determine artifact coordinates from: " + pom);
+            return Extension.createNotDetected();
         }
 
         boolean commonOrInternal = false;
@@ -142,7 +151,7 @@ private Extension getExtensionFromPom(Path pom, Document doc) {
             }
         }
 
-        return new Extension(groupId, artifactId, name, nameSource);
+        return new Extension(groupId, artifactId, name, nameSource, true);
     }
 
     private Optional<String> getExtensionNameFromExtensionMetadata() {

core/processor/src/main/java/io/quarkus/annotation/processor/util/FilerUtil.java

@@ -133,12 +133,18 @@ public Path getTargetPath() {
         }
     }
 
-    public Path getPomPath() {
+    public Optional<Path> getPomPath() {
         try {
-            return Paths.get(processingEnv.getFiler().getResource(StandardLocation.CLASS_OUTPUT, "", "dummy").toUri())
-                    .getParent().getParent().getParent().resolve("pom.xml").toAbsolutePath();
+            Path pomPath = Paths.get(processingEnv.getFiler().getResource(StandardLocation.CLASS_OUTPUT, "", "dummy").toUri())
+                    .getParent().getParent().getParent().resolve("pom.xml");
+
+            if (!Files.isReadable(pomPath)) {
+                return Optional.empty();
+            }
+
+            return Optional.of(pomPath.toAbsolutePath());
         } catch (IOException e) {
-            throw new IllegalStateException("Unable to determine path to pom.xml");
+            return Optional.empty();
         }
     }
 

core/processor/src/main/java/io/quarkus/annotation/processor/util/Utils.java

@@ -15,7 +15,7 @@ public Utils(ProcessingEnvironment processingEnv) {
         this.elementUtil = new ElementUtil(processingEnv);
         this.accessorGenerator = new AccessorGenerator(processingEnv, elementUtil);
         this.filerUtil = new FilerUtil(processingEnv);
-        this.extensionUtil = new ExtensionUtil(filerUtil);
+        this.extensionUtil = new ExtensionUtil(processingEnv, filerUtil);
     }
 
     public ElementUtil element() {