From 076ee562e3647117e9d1374e4a9e88204ac54b64 Mon Sep 17 00:00:00 2001
From: James Agnew <jamesagnew@gmail.com>
Date: Thu, 6 Feb 2020 11:16:17 -0500
Subject: [PATCH] Avoid trying to fetch SD by null URL (test case added)

---
 .../java/org/hl7/fhir/r5/validation/InstanceValidator.java  | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/InstanceValidator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/InstanceValidator.java
index 2e831205c..5accd1aef 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/InstanceValidator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/InstanceValidator.java
@@ -1720,7 +1720,11 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
                 ok = true;
                 break;
               }
-              sd = context.fetchResource(StructureDefinition.class, sd.getBaseDefinition());
+              if (sd.getBaseDefinition() != null) {
+                sd = context.fetchResource(StructureDefinition.class, sd.getBaseDefinition());
+              } else {
+                sd = null;
+              }
             }
           }
         }