Throw IllegalArgumentException when getManifest is called without Session and classpath is enabled

src/main/java/org/apache/maven/shared/archiver/MavenArchiver.java

@@ -254,6 +254,10 @@ protected Manifest doGetManifest(
 
         DependencyResolverResult result;
         if (config.isAddClasspath() || config.isAddExtensions()) {
+            if (session == null) {
+                throw new IllegalArgumentException("Session is required when addClasspath or addExtensions is enabled. "
+                        + "Use getManifest(Session, Project, ManifestConfiguration) instead.");
+            }
             result = session.getService(DependencyResolver.class).resolve(session, project, PathScope.MAIN_RUNTIME);
         } else {
             result = null;

src/test/java/org/apache/maven/shared/archiver/MavenArchiverTest.java

@@ -96,6 +96,18 @@ void setup() {
         when(dependencyResolverResult.getDependencies()).thenReturn(dependencies);
     }
 
+    @Test
+    void getManifestWithoutSessionWhenAddClasspath() {
+        MavenArchiver archiver = new MavenArchiver();
+        Project project = getDummyProject();
+        ManifestConfiguration config = new ManifestConfiguration();
+        config.setAddClasspath(true);
+
+        assertThatExceptionOfType(IllegalArgumentException.class)
+                .isThrownBy(() -> archiver.getManifest(project, config))
+                .withMessageContaining("Session");
+    }
+
     @ParameterizedTest
     @EmptySource
     @ValueSource(