From eb7cdefaaa90143b55c70febf5e67e14831fdb38 Mon Sep 17 00:00:00 2001
From: Tamas Cservenak <tamas@cservenak.net>
Date: Thu, 13 Apr 2023 11:56:13 +0200
Subject: [PATCH] [MNG-7759] Maven2 plugins will not have even session setter
 (#1084)

As setter was added in Maven3. Still, this causes unexpected NPE
during plugin execution, while Maven3 should support Maven2
plugins.

---

https://issues.apache.org/jira/browse/MNG-7759
---
 .../java/org/apache/maven/project/DefaultProjectBuilder.java  | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java b/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java
index 00498cf39c0b..9fa8f3c22baa 100644
--- a/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java
+++ b/maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java
@@ -1000,6 +1000,10 @@ class InternalConfig {
     }
 
     private ModelCache createModelCache(RepositorySystemSession session) {
+        // MNG-7759: very old clients (Maven2 plugins) will not even have session, as setter was added in Maven 3
+        if (session == null) {
+            return null;
+        }
         // MNG-7693: for older clients (not injecting ModelCacheFactory), make this work OOTB w/ defaults
         return modelCacheFactory != null
                 ? modelCacheFactory.createCache(session)