GitHub Issue 952: Registry containing MVTC import succeeds with error message

api/src/org/labkey/api/dataiterator/MapDataIterator.java

@@ -18,6 +18,7 @@
 import org.apache.commons.lang3.StringUtils;
 import org.apache.logging.log4j.Logger;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.labkey.api.collections.ArrayListMap;
 import org.labkey.api.collections.CaseInsensitiveHashMap;
 import org.labkey.api.collections.CaseInsensitiveTreeSet;
@@ -43,7 +44,17 @@ public interface MapDataIterator extends DataIterator
     Logger LOGGER = LogHelper.getLogger(MapDataIterator.class, "DataIterators backed by Maps");
 
     boolean supportsGetMap();
-    Map<String,Object> getMap();
+    @Nullable Map<String,Object> getMap();
+    default @Nullable Map<String, Object> getMapExcludeExistingRecord()
+    {
+        Map<String, Object> row = getMap();
+        if (null == row)
+            return null;
+
+        Map<String, Object> rowClean = new CaseInsensitiveHashMap<>(row);
+        rowClean.remove(ExistingRecordDataIterator.EXISTING_RECORD_COLUMN_NAME);
+        return rowClean;
+    }
 
     /**
      * wrap an existing DataIterator to add MapDataIterator interface

api/src/org/labkey/api/query/AbstractQueryUpdateService.java

@@ -465,7 +465,7 @@ public boolean next() throws BatchValidationException
                     {
                         boolean ret = super.next();
                         if (ret)
-                            rows.add(((MapDataIterator)_delegate).getMap());
+                            rows.add(((MapDataIterator)_delegate).getMapExcludeExistingRecord());
                         return ret;
                     }
                 };

experiment/src/org/labkey/experiment/api/SampleTypeUpdateServiceDI.java

@@ -343,7 +343,7 @@ else if (nameObj instanceof Number)
                                     }
                                 }
                                 else
-                                    rows.add(((MapDataIterator) _delegate).getMap());
+                                    rows.add(((MapDataIterator) _delegate).getMapExcludeExistingRecord());
                             }
                             return ret;
                         }