diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java
index 25a19cc83..554dc8608 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java
@@ -3864,5 +3864,9 @@ public class ProfileUtilities extends TranslatingUtilities {
       return null;
   }
 
+  public static boolean isExtensionDefinition(StructureDefinition sd) {
+    return sd.getDerivation() == TypeDerivationRule.CONSTRAINT && sd.getType().equals("Extension");
+  }
+
   
 }
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/ContextUtilities.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/ContextUtilities.java
index fe714306e..822efd798 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/ContextUtilities.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/context/ContextUtilities.java
@@ -136,12 +136,24 @@ public class ContextUtilities implements ProfileKnowledgeProvider {
    * @return a list of the resource and type names defined for this version
    */
   public List<String> getTypeNames() {
-    List<String> result = new ArrayList<String>();
+    Set<String> result = new HashSet<String>();
+    for (StructureDefinition sd : context.fetchResourcesByType(StructureDefinition.class)) {
+      if (sd.getKind() != StructureDefinitionKind.LOGICAL && sd.getDerivation() == TypeDerivationRule.SPECIALIZATION)
+        result.add(sd.getName());
+    }
+    return Utilities.sorted(result);
+  }
+
+
+  /**
+   * @return a set of the resource and type names defined for this version
+   */
+  public Set<String> getTypeNameSet() {
+    Set<String> result = new HashSet<String>();
     for (StructureDefinition sd : context.fetchResourcesByType(StructureDefinition.class)) {
       if (sd.getKind() != StructureDefinitionKind.LOGICAL && sd.getDerivation() == TypeDerivationRule.SPECIALIZATION)
         result.add(sd.getName());
     }
-    Collections.sort(result);
     return result;
   }