diff --git a/common/build.gradle b/common/build.gradle
--- a/common/build.gradle
+++ b/common/build.gradle
@@ -6,6 +6,9 @@ plugins {
 java {
     withJavadocJar()
     withSourcesJar()
+        toolchain {
+        languageVersion = JavaLanguageVersion.of(17)
+    }
 }
 
 dependencies {
@@ -14,7 +17,7 @@ dependencies {
 
 task printVersion{
     doLast {
-        println "project: $project.groupId:$project.name:$project.version"
+        println "project: $project.group:$project.name:$project.version"
         println "jar: ${->jar.archiveFileName.get()}"
     }
 }
@@ -25,4 +28,12 @@ publishing {
             url "${System.properties["user.home"]}/ivy-repo"
         }
     }
+    publications {
+        ivy(IvyPublication) {
+            from components.java
+            descriptor.description {
+                text = providers.provider({ description })
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/common/src/main/java/org/implab/gradle/common/ProjectMixin.java b/common/src/main/java/org/implab/gradle/common/ProjectMixin.java
--- a/common/src/main/java/org/implab/gradle/common/ProjectMixin.java
+++ b/common/src/main/java/org/implab/gradle/common/ProjectMixin.java
@@ -10,6 +10,7 @@ import org.gradle.api.Task;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.Directory;
 import org.gradle.api.tasks.TaskProvider;
+import org.implab.gradle.common.utils.ExtraProps;
 
 /** Project configuration traits */
 public interface ProjectMixin {
@@ -37,6 +38,15 @@ public interface ProjectMixin {
         return getProject().getPlugins().findPlugin(clazz);
     }
 
+    /**
+     * @param classes The list of classes to register as extensions
+     */
+    default void exportClasses(Class<?>... classes) {
+        var props = ExtraProps.of(getProject());
+        for (var clazz : classes)
+            props.put(clazz.getSimpleName(), clazz);
+    }
+
     /** Creates and register a new project extension.
      * 
      * @param <T> The type of the extension
diff --git a/common/src/main/java/org/implab/gradle/common/utils/ExtraProps.java b/common/src/main/java/org/implab/gradle/common/utils/ExtraProps.java
--- a/common/src/main/java/org/implab/gradle/common/utils/ExtraProps.java
+++ b/common/src/main/java/org/implab/gradle/common/utils/ExtraProps.java
@@ -7,10 +7,10 @@ import org.gradle.api.plugins.ExtensionA
 public class ExtraProps {
 
     public static Map<String, Object> of(Object target) {
-        return switch (target) {
-            case ExtensionAware ext -> ext.getExtensions().getExtraProperties().getProperties();
-            default -> Map.of();
-        };
+        if (target instanceof ExtensionAware ext)
+            return ext.getExtensions().getExtraProperties().getProperties();
+        else
+            return Map.of();
     }
 
 }
diff --git a/gradle/gradle.properties b/gradle.properties
rename from gradle/gradle.properties
rename to gradle.properties
--- a/gradle/gradle.properties
+++ b/gradle.properties
@@ -1,2 +1,2 @@
-groupId=org.implab.gradle
+group=org.implab.gradle
 version=1.0
\ No newline at end of file