From 4d701f6c52c2014cb008341c5578fc8cbb9f567a Mon Sep 17 00:00:00 2001
From: Basil Crow <me@basilcrow.com>
Date: Tue, 6 Dec 2022 23:12:45 -0800
Subject: [PATCH] Decline to cache a likely incorrect computation

---
 core/src/main/java/jenkins/model/Jenkins.java | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/jenkins/model/Jenkins.java b/core/src/main/java/jenkins/model/Jenkins.java
index d065df8065317..dc845a0e2cad3 100644
--- a/core/src/main/java/jenkins/model/Jenkins.java
+++ b/core/src/main/java/jenkins/model/Jenkins.java
@@ -1267,7 +1267,14 @@ public synchronized Set<String> getAgentProtocols() {
                     result.add(name);
                 }
             }
-            agentProtocols = result;
+            /*
+             * An empty result is almost never valid, but it can happen due to JENKINS-70206. Since we know the result
+             * is likely incorrect, at least decline to cache it so that a correct result can be computed later on
+             * rather than continuing to deliver the incorrect result indefinitely.
+             */
+            if (!result.isEmpty()) {
+                agentProtocols = result;
+            }
             return result;
         }
         return agentProtocols;