File reproducible-javadoc-timestamp.patch of Package java-11-openjdk.34818

diff --git a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Head.java b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Head.java
index b227ef5fb8..ac186f4e52 100644
--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Head.java
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Head.java
@@ -256,6 +256,9 @@ public class Head {
      */
     public Content toContent() {
         Date now = showTimestamp ? calendar.getTime() : null;
+        if (now != null && System.getenv("SOURCE_DATE_EPOCH") != null) {
+            now = new Date(1000 * Long.parseLong(System.getenv("SOURCE_DATE_EPOCH")));
+        }
 
         HtmlTree tree = new HtmlTree(HtmlTag.HEAD);
         if (showGeneratedBy) {
@@ -269,6 +272,9 @@ public class Head {
 
         if (showMetaCreated) {
             SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
+            if (System.getenv("SOURCE_DATE_EPOCH") != null) {
+                dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+            }
             tree.add(HtmlTree.META(
                     (htmlVersion == HtmlVersion.HTML5) ? "dc.created" : "date",
                     dateFormat.format(now)));
@@ -298,7 +304,14 @@ public class Head {
     private Comment getGeneratedBy(boolean timestamp, Date now) {
         String text = "Generated by javadoc"; // marker string, deliberately not localized
         if (timestamp) {
-            text += " ("+ docletVersion + ") on " + now;
+            text += " ("+ docletVersion + ") on ";
+            if (System.getenv("SOURCE_DATE_EPOCH") == null) {
+                text += now;
+            } else {
+                SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
+                fmt.setTimeZone(TimeZone.getTimeZone("UTC"));
+                text += fmt.format(now);
+            }
         }
         return new Comment(text);
     }