From ebf706b837ea8c1c9cf96641e1e1e5796fa09d19 Mon Sep 17 00:00:00 2001
From: Grahame Grieve <grahameg@gmail.ccom>
Date: Mon, 18 Sep 2023 17:06:31 +1000
Subject: [PATCH] Fix NPE in version comparison

---
 .../java/org/hl7/fhir/r5/comparison/ComparisonSession.java     | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonSession.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonSession.java
index 3c05b67dc..94745f47b 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonSession.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/comparison/ComparisonSession.java
@@ -180,6 +180,9 @@ public class ComparisonSession {
   }
 
   private VersionComparisonAnnotation getAnnotation(Base b) {
+    if (b == null) {
+      return null;
+    }
     if (b.hasUserData(VersionComparisonAnnotation.USER_DATA_NAME)) {
       return (VersionComparisonAnnotation) b.getUserData(VersionComparisonAnnotation.USER_DATA_NAME);
     } else {