.stapler file generation is nondeterministic (#527)

core/src/main/java/org/kohsuke/stapler/jsr269/AbstractProcessorImpl.java

@@ -26,11 +26,14 @@
 import javax.annotation.processing.AbstractProcessor;
 import javax.lang.model.element.Element;
 import javax.tools.FileObject;
+import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.io.Writer;
 import java.util.Properties;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import static javax.tools.Diagnostic.Kind.*;
 import static javax.tools.StandardLocation.*;
@@ -66,8 +69,13 @@ protected void notice(String msg, Element location) {
 
     protected void writePropertyFile(Properties p, String name) throws IOException {
         FileObject f = createResource(name);
-        try (OutputStream os = f.openOutputStream()) {
-            p.store(os,null);
+        /*
+         * This is somewhat fragile, but it is the only practical option on Java 11 and 17. In Java 21, we could instead
+         * set the "java.properties.date" system property to a fixed string and avoid the need to work around internal
+         * Java Platform implementation details.
+         */
+        try (Writer w = f.openWriter(); BufferedWriter bw = new CommentStrippingBufferedWriter(w)) {
+            p.store(bw,null);
         }
     }
 
@@ -78,4 +86,19 @@ protected FileObject getResource(String name) throws IOException {
     protected FileObject createResource(String name) throws IOException {
         return processingEnv.getFiler().createResource(CLASS_OUTPUT, "", name);
     }
+
+    private static class CommentStrippingBufferedWriter extends BufferedWriter {
+        private final AtomicInteger count = new AtomicInteger(0);
+
+        public CommentStrippingBufferedWriter(Writer out) {
+            super(out);
+        }
+
+        @Override
+        public void write(String str) throws IOException {
+            if (count.getAndIncrement() > 0 || !str.startsWith("#")) {
+                super.write(str);
+            }
+        }
+    }
 }

core/src/test/java/org/kohsuke/stapler/jsr269/ConstructorProcessorTest.java

@@ -1,5 +1,8 @@
 package org.kohsuke.stapler.jsr269;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -8,6 +11,7 @@
 import com.karuslabs.elementary.junit.annotations.Inline;
 import com.karuslabs.elementary.junit.annotations.Options;
 import com.karuslabs.elementary.junit.annotations.Processors;
+import java.time.Year;
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
@@ -160,4 +164,22 @@ void duplicatedButNotAnnotatedConstructor(Results results) {
         assertEquals(0, diagnostics.size());
     }
     // TODO nested classes use qualified rather than binary name
+
+    //issue-526
+    @Inline(
+            name = "some.pkg.Stuff",
+            source = {
+                "package some.pkg;",
+                "import org.kohsuke.stapler.DataBoundConstructor;",
+                "public class Stuff {",
+                "  @DataBoundConstructor public Stuff(int count, String name) {}",
+                "}",
+            })
+    @Test
+    void reproducibleBuild(Results results) {
+        assertEquals(Collections.emptyList(), results.diagnostics);
+        assertThat(
+                Utils.getGeneratedResource(results.sources, "some/pkg/Stuff.stapler"),
+                not(containsString(Integer.toString(Year.now().getValue()))));
+    }
 }