Fix NPE in ReverseBuildTrigger due to null upstream threshold (JENKINS-39044)

Author: Zenith1415

core/src/main/java/jenkins/triggers/ReverseBuildTrigger.java

@@ -166,7 +166,7 @@ private boolean shouldTrigger(Run upstreamBuild, TaskListener listener) {
             return false;
         }
         Result result = upstreamBuild.getResult();
-        return result != null && result.isBetterOrEqualTo(threshold);
+        return result != null && result.isBetterOrEqualTo(threshold != null ? threshold : Result.SUCCESS);
     }
 
     @Override public void buildDependencyGraph(final AbstractProject downstream, DependencyGraph graph) {

core/src/test/java/hudson/model/ResultTest.java

@@ -0,0 +1,48 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2012 Jesse Glick.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package hudson.model;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+public class ResultTest {
+
+    @Test
+    public void testIsBetterOrEqualToHandlesNull() {
+        // This used to throw NPE [JENKINS-39044]
+        // We assume nothing is "better or equal" to a null/undefined requirement
+        assertFalse(Result.SUCCESS.isBetterOrEqualTo(null), "Comparing against null should not crash");
+    }
+
+    @Test
+    public void testIsBetterOrEqualToBasic() {
+        // Verify standard logic still works
+        assertTrue(Result.SUCCESS.isBetterOrEqualTo(Result.FAILURE));
+        assertTrue(Result.SUCCESS.isBetterOrEqualTo(Result.SUCCESS));
+        assertFalse(Result.FAILURE.isBetterOrEqualTo(Result.SUCCESS));
+    }
+}