diff -urEbwB maven-jar-plugin-3.4.2.orig/src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java maven-jar-plugin-3.4.2/src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java
--- maven-jar-plugin-3.4.2.orig/src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java	2025-06-06 18:06:45.024404142 +0200
+++ maven-jar-plugin-3.4.2/src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java	2025-06-06 18:08:10.461673694 +0200
@@ -348,7 +348,7 @@
                 projectHelper.attachArtifact(getProject(), getType(), getClassifier(), jarFile);
             } else {
                 if (projectHasAlreadySetAnArtifact()) {
-                    throw new MojoExecutionException("You have to use a classifier "
+                    getLog().warn("You have to use a classifier "
                             + "to attach supplemental artifacts to the project instead of replacing them.");
                 }
                 getProject().getArtifact().setFile(jarFile);