--- maven-jar-plugin-3.3.0/src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java	2024-09-23 11:44:25.479106748 +0200
+++ maven-jar-plugin-3.3.0/src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java	2024-09-23 12:10:05.439871672 +0200
@@ -251,6 +251,14 @@
         archiver.setArchiver( (JarArchiver) archivers.get( archiverName ) );
         archiver.setOutputFile( jarFile );
 
+        if ( outputTimestamp == null ||
+            outputTimestamp.length() < 1 ||
+            ( ( outputTimestamp.length() == 1 )
+                && !Character.isDigit( outputTimestamp.charAt(0) ) ) )
+        {
+            outputTimestamp = System.getenv("SOURCE_DATE_EPOCH");
+        }
+
         // configure for Reproducible Builds based on outputTimestamp value
         archiver.configureReproducibleBuild( outputTimestamp );