Whether the --date option is supported depends on the Java version.

Author: desruisseaux

src/it/MJAR-275-reproducible-module-info/invoker.properties

@@ -5,17 +5,15 @@
 # to you under the Apache License, Version 2.0 (the
 # "License"); you may not use this file except in compliance
 # with the License.  You may obtain a copy of the License at
-# 
+#
 #   http://www.apache.org/licenses/LICENSE-2.0
-# 
+#
 # Unless required by applicable law or agreed to in writing,
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
 
-# NOTE: Requires Java 10+ to compile the module declaration for Java 9+,
-# this is due that compiling the module declaration generates a
-# module descriptor with the JDK version on it, making it unreproducible.
-invoker.java.version = 10+
+# The --date option needed for reproducible build is available only since Java 19.
+invoker.java.version = 19+

src/main/java/org/apache/maven/plugins/jar/AbstractJarMojo.java

@@ -18,6 +18,8 @@
  */
 package org.apache.maven.plugins.jar;
 
+import javax.lang.model.SourceVersion;
+
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -230,6 +232,20 @@ protected ToolProvider getJarTool() throws MojoException {
         return ToolProvider.findFirst(toolId).orElseThrow(() -> new MojoException("No such \"" + toolId + "\" tool."));
     }
 
+    /**
+     * Returns whether the specified Java version is supported.
+     *
+     * @param release name of an {@link SourceVersion} enumeration constant
+     * @return whether the current environment support that version
+     */
+    private static boolean isSupported(String release) {
+        try {
+            return SourceVersion.latestSupported().compareTo(SourceVersion.valueOf(release)) >= 0;
+        } catch (IllegalArgumentException e) {
+            return false;
+        }
+    }
+
     /**
      * Returns the output time stamp or, as a fallback, the {@code SOURCE_DATE_EPOCH} environment variable.
      * If the time stamp is expressed in seconds, it is converted to ISO 8601 format. Otherwise it is returned as-is.
@@ -246,6 +262,10 @@ protected String getOutputTimestamp() {
                 return null;
             }
         }
+        if (!isSupported("RELEASE_19")) {
+            log.warn("Reproducible build requires Java 19 or later.");
+            return null;
+        }
         for (int i = time.length(); --i >= 0; ) {
             char c = time.charAt(i);
             if ((c < '0' || c > '9') && (i != 0 || c != '-')) {