diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/InstanceValidator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/InstanceValidator.java
index 5692b2246..6d13e8275 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/InstanceValidator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/InstanceValidator.java
@@ -130,6 +130,7 @@ import org.hl7.fhir.r5.validation.BaseValidator;
 import org.hl7.fhir.r5.validation.EnableWhenEvaluator;
 import org.hl7.fhir.r5.validation.EnableWhenEvaluator.QStack;
 import org.hl7.fhir.r5.validation.XVerExtensionManager;
+import org.hl7.fhir.r5.validation.instancevalidator.utils.ChildIterator;
 import org.hl7.fhir.r5.validation.instancevalidator.utils.IndexedElement;
 import org.hl7.fhir.r5.validation.instancevalidator.utils.ResolvedReference;
 import org.hl7.fhir.utilities.CommaSeparatedStringBuilder;
@@ -2899,7 +2900,7 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
     return false;
   }
 
-  private boolean isPrimitiveType(String code) {
+  public boolean isPrimitiveType(String code) {
     StructureDefinition sd = context.fetchTypeDefinition(code);
     return sd != null && sd.getKind() == StructureDefinitionKind.PRIMITIVETYPE;
   }
@@ -5203,7 +5204,7 @@ private boolean isAnswerRequirementFulfilled(QuestionnaireItemComponent qItem, L
   public List<ElementInfo> listChildren(Element element, NodeStack stack) {
     // 1. List the children, and remember their exact path (convenience)
     List<ElementInfo> children = new ArrayList<InstanceValidator.ElementInfo>();
-    ChildIterator iter = new ChildIterator(stack.getLiteralPath(), element);
+    ChildIterator iter = new ChildIterator(this, stack.getLiteralPath(), element);
     while (iter.next())
       children.add(new ElementInfo(iter.name(), iter.element(), iter.path(), iter.count()));
     return children;
@@ -5496,72 +5497,7 @@ private boolean isAnswerRequirementFulfilled(QuestionnaireItemComponent qItem, L
     return Calendar.getInstance().get(Calendar.YEAR);
   }
 
-  public class ChildIterator {
-    private String basePath;
-    private Element parent;
-    private int cursor;
-    private int lastCount;
-
-    public ChildIterator(String path, Element element) {
-      parent = element;
-      basePath = path;
-      cursor = -1;
-    }
-
-    public int count() {
-      String nb = cursor == 0 ? "--" : parent.getChildren().get(cursor-1).getName();
-      String na = cursor >= parent.getChildren().size() - 1 ? "--" : parent.getChildren().get(cursor+1).getName();
-      if (name().equals(nb) || name().equals(na) ) {
-        return lastCount;
-      } else
-        return -1;
-    }
-
-    public Element element() {
-      return parent.getChildren().get(cursor);
-    }
-
-    public String name() {
-      return element().getName();
-    }
-
-    public boolean next() {
-      if (cursor == -1) {
-        cursor++;
-        lastCount = 0;
-      } else {
-        String lastName = name();
-        cursor++;
-        if (cursor < parent.getChildren().size() && name().equals(lastName))
-          lastCount++;
-        else
-          lastCount = 0;
-      }
-      return cursor < parent.getChildren().size();
-    }
-
-    public String path() {
-      int i = count();
-      String sfx = "";
-      String n = name();
-      String fn = "";
-      if (element().getProperty().isChoice()) {
-        String en = element().getProperty().getName();
-        en = en.substring(0, en.length()-3);
-        String t = n.substring(en.length());
-        if (isPrimitiveType(Utilities.uncapitalize(t)))
-          t = Utilities.uncapitalize(t);
-        n = en;
-        fn = ".ofType("+t+")";       
-      }
-      if (i > -1 || (element().getSpecial() == null && element().isList())) {
-        sfx = "[" + Integer.toString(lastCount) + "]";
-      }
-      return basePath + "." + n + sfx+fn;
-    }
-  }
-
-  public class NodeStack {
+    public class NodeStack {
     private ElementDefinition definition;
     private Element element;
     private ElementDefinition extension;
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/utils/ChildIterator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/utils/ChildIterator.java
new file mode 100644
index 000000000..09e35d78c
--- /dev/null
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/r5/validation/instancevalidator/utils/ChildIterator.java
@@ -0,0 +1,112 @@
+package org.hl7.fhir.r5.validation.instancevalidator.utils;
+
+import org.hl7.fhir.r5.elementmodel.Element;
+import org.hl7.fhir.r5.validation.instancevalidator.InstanceValidator;
+import org.hl7.fhir.utilities.Utilities;
+
+public class ChildIterator {
+    private final InstanceValidator instanceValidator;
+    private String basePath;
+    private Element parent;
+    private int cursor;
+    private int lastCount;
+
+    public ChildIterator(InstanceValidator instanceValidator, String path, Element element) {
+        this.instanceValidator = instanceValidator;
+        parent = element;
+        basePath = path;
+        cursor = -1;
+    }
+
+    public InstanceValidator getInstanceValidator() {
+        return instanceValidator;
+    }
+
+    public String getBasePath() {
+        return basePath;
+    }
+
+    public ChildIterator setBasePath(String basePath) {
+        this.basePath = basePath;
+        return this;
+    }
+
+    public Element getParent() {
+        return parent;
+    }
+
+    public ChildIterator setParent(Element parent) {
+        this.parent = parent;
+        return this;
+    }
+
+    public int getCursor() {
+        return cursor;
+    }
+
+    public ChildIterator setCursor(int cursor) {
+        this.cursor = cursor;
+        return this;
+    }
+
+    public int getLastCount() {
+        return lastCount;
+    }
+
+    public ChildIterator setLastCount(int lastCount) {
+        this.lastCount = lastCount;
+        return this;
+    }
+
+    public Element element() {
+        return parent.getChildren().get(cursor);
+    }
+
+    public String name() {
+        return element().getName();
+    }
+
+    public int count() {
+        String nb = cursor == 0 ? "--" : parent.getChildren().get(cursor - 1).getName();
+        String na = cursor >= parent.getChildren().size() - 1 ? "--" : parent.getChildren().get(cursor + 1).getName();
+        if (name().equals(nb) || name().equals(na)) {
+            return lastCount;
+        } else
+            return -1;
+    }
+
+    public boolean next() {
+        if (cursor == -1) {
+            cursor++;
+            lastCount = 0;
+        } else {
+            String lastName = name();
+            cursor++;
+            if (cursor < parent.getChildren().size() && name().equals(lastName))
+                lastCount++;
+            else
+                lastCount = 0;
+        }
+        return cursor < parent.getChildren().size();
+    }
+
+    public String path() {
+        int i = count();
+        String sfx = "";
+        String n = name();
+        String fn = "";
+        if (element().getProperty().isChoice()) {
+            String en = element().getProperty().getName();
+            en = en.substring(0, en.length() - 3);
+            String t = n.substring(en.length());
+            if (instanceValidator.isPrimitiveType(Utilities.uncapitalize(t)))
+                t = Utilities.uncapitalize(t);
+            n = en;
+            fn = ".ofType(" + t + ")";
+        }
+        if (i > -1 || (element().getSpecial() == null && element().isList())) {
+            sfx = "[" + Integer.toString(lastCount) + "]";
+        }
+        return basePath + "." + n + sfx + fn;
+    }
+}