--- apache-ant-1.10.14/src/main/org/apache/tools/ant/taskdefs/Jar.java	2024-07-16 13:38:38.336428941 +0200
+++ apache-ant-1.10.14/src/main/org/apache/tools/ant/taskdefs/Jar.java	2024-07-16 13:48:05.794045414 +0200
@@ -450,6 +450,13 @@
         serviceList.add(service);
     }
 
+    private long currentTimeMillisOrSourceDateEpoch() {
+        if ( System.getenv("SOURCE_DATE_EPOCH") != null ) {
+            return 1000 * Long.parseLong(System.getenv("SOURCE_DATE_EPOCH"));
+        }
+        return System.currentTimeMillis();
+    }
+
     /**
      * Write SPI Information to JAR
      */
@@ -459,7 +466,7 @@
                 //stolen from writeManifest
                super.zipFile(is, zOut,
                              "META-INF/services/" + service.getType(),
-                             System.currentTimeMillis(), null,
+                             currentTimeMillisOrSourceDateEpoch(), null,
                              ZipFileSet.DEFAULT_FILE_MODE);
            }
         }
@@ -579,7 +586,7 @@
             new ByteArrayInputStream(baos.toByteArray());
         try {
             super.zipFile(bais, zOut, MANIFEST_NAME,
-                          System.currentTimeMillis(), null,
+                          currentTimeMillisOrSourceDateEpoch(), null,
                           ZipFileSet.DEFAULT_FILE_MODE);
         } finally {
             // not really required
@@ -656,7 +663,7 @@
         writer.close();
         try (ByteArrayInputStream bais =
             new ByteArrayInputStream(baos.toByteArray())) {
-            super.zipFile(bais, zOut, INDEX_NAME, System.currentTimeMillis(),
+            super.zipFile(bais, zOut, INDEX_NAME, currentTimeMillisOrSourceDateEpoch(),
                           null, ZipFileSet.DEFAULT_FILE_MODE);
         }
     }