diff --git a/TMBuilder/README.md b/TMBuilder/README.md
index e50e128..32103fb 100644
--- a/TMBuilder/README.md
+++ b/TMBuilder/README.md
@@ -24,6 +24,7 @@ Executable requires Java 8 or later. Download is available under [releases](http
   
 | Version  | Notes                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
 |---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 3.2.1 | Allow core validation set to be exported as developer mock. |
 | 3.2.0 | Adding null check option to each of the node types so it is possible to check for null response values. |
 | 3.1.2 | Fix check review bug and formatting. |
 | 3.1.1 | Fix export developer mock dialog selection messaging. Eliminating confusion around the file filter referencing Java and Kotlin classes which are not necessary when exporting developer mocks.                                                                                                                                                                                                                                                                                                                   |
diff --git a/TMBuilder/pom.xml b/TMBuilder/pom.xml
index 6f1b3c7..e7ef48a 100644
--- a/TMBuilder/pom.xml
+++ b/TMBuilder/pom.xml
@@ -8,7 +8,7 @@
 
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>tmbuilder</artifactId>
-	<version>3.2.0</version>
+	<version>3.2.1</version>
 	<name>TMBuilder</name>
 	<description>Thin Model Builder (TMBuilder) for NST thin models.</description>
 
diff --git a/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/TMGuiConstants.java b/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/TMGuiConstants.java
index 1220f68..eb38939 100644
--- a/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/TMGuiConstants.java
+++ b/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/TMGuiConstants.java
@@ -2,7 +2,7 @@
 
 public class TMGuiConstants {
 
-  public static final String APP_NAME = "TMBuilder v3.2.0";
+  public static final String APP_NAME = "TMBuilder v3.2.1";
   public static final int DEFAULT_WINDOW_WIDTH = 1000;
   public static final int DEFAULT_WINDOW_HEIGHT = 800;
   public static final String DICTIONARY_KEY = "<key>";
diff --git a/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExport.java b/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExport.java
index 2040181..23c63ba 100644
--- a/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExport.java
+++ b/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExport.java
@@ -32,23 +32,29 @@ public class DeveloperMockExport {
     public void export(File exportPath, List<ValidationSetModel> validationSetModels) throws IOException, ClassNotFoundException {
 
         ValidationSetModel coreValidationSet = getCoreValidationSet(validationSetModels);
-
+        String validationSetName = coreValidationSet.getValidationSetName();
+        validationSetName = camelCaseValidationSetName(validationSetName);
+        writeDeveloperMock(exportPath, validationSetName, getJsonFromValidationSet(coreValidationSet, coreValidationSet));
 
         for (ValidationSetModel validationSetModel : validationSetModels) {
 
             String json = getJsonFromValidationSet(coreValidationSet, validationSetModel);
 
-            String validationSetName = validationSetModel.getValidationSetName();
+            validationSetName = validationSetModel.getValidationSetName();
             validationSetName = camelCaseValidationSetName(validationSetName);
 
-            String fileName = String.format(DEVELOPER_MOCK_FILE_NAME_FORMAT, validationSetName);
-            File exportFile = new File(exportPath, fileName);
-            FileWriter fileWriter = new FileWriter(exportFile);
-            fileWriter.write(json);
-            fileWriter.close();
+            writeDeveloperMock(exportPath, validationSetName, json);
         }
     }
 
+    protected void writeDeveloperMock(File exportPath, String validationSetName, String json) throws IOException {
+        String fileName = String.format(DEVELOPER_MOCK_FILE_NAME_FORMAT, validationSetName);
+        File exportFile = new File(exportPath, fileName);
+        FileWriter fileWriter = new FileWriter(exportFile);
+        fileWriter.write(json);
+        fileWriter.close();
+    }
+
     public String getJsonFromValidationSet(ValidationSetModel coreValidationSet, ValidationSetModel customValidationSet) throws IOException, ClassNotFoundException {
 
         TreeMap<String, Integer> coreValidationArrayPathToArraySizeMap = ArrayPathToArraySizeMapProcessor.getArrayPathToArraySizeMap(coreValidationSet);
@@ -58,8 +64,10 @@ public String getJsonFromValidationSet(ValidationSetModel coreValidationSet, Val
         TreeMap<String, Integer> arrayPathToArraySizeMap = new TreeMap<>(new SmallestToLargestArrayPathComparator());
         arrayPathToArraySizeMap.putAll(coreValidationArrayPathToArraySizeMap);
 
-        TreeMap<String, Integer> customValidationArrayPathToArraySizeMap = ArrayPathToArraySizeMapProcessor.getArrayPathToArraySizeMap(customValidationSet);
-        arrayPathToArraySizeMap.putAll(customValidationArrayPathToArraySizeMap);
+        if (customValidationSet != null) {
+            TreeMap<String, Integer> customValidationArrayPathToArraySizeMap = ArrayPathToArraySizeMapProcessor.getArrayPathToArraySizeMap(customValidationSet);
+            arrayPathToArraySizeMap.putAll(customValidationArrayPathToArraySizeMap);
+        }
 
         // Build up the jsonMap structure.
         Map<String, Object> jsonMap = new HashMap<>();
@@ -67,7 +75,10 @@ public String getJsonFromValidationSet(ValidationSetModel coreValidationSet, Val
 
         // Populate the jsonMap with mock values.
         JsonMapPopulateProcessor.populateJsonMapWithMockValues(coreValidationSet, jsonMap);
-        JsonMapPopulateProcessor.populateJsonMapWithMockValues(customValidationSet, jsonMap);
+
+        if (customValidationSet != null) {
+            JsonMapPopulateProcessor.populateJsonMapWithMockValues(customValidationSet, jsonMap);
+        }
 
         // Write the JSON to file.
         String json = gson.toJson(jsonMap);
diff --git a/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessor.java b/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessor.java
index 73e837a..6a0daa5 100644
--- a/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessor.java
+++ b/TMBuilder/src/main/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessor.java
@@ -25,10 +25,12 @@ public static Map<String, Object> getJsonMapForValidations(TreeMap<String, Integ
         // Iterate over each path from both the coreValidationSetModel and the customValidationSetModel, using the
         // arrayPathToSizeMap to initialize array nodes to the right size.
         NodeModel[] coreNodes = coreValidationSetModel.getData();
-        NodeModel[] customNodes = customValidationSetModel.getData();
-
         processNodeModels(coreNodes, arrayPathToSizeMap, jsonMap);
-        processNodeModels(customNodes, arrayPathToSizeMap, jsonMap);
+
+        if (customValidationSetModel != null) {
+            NodeModel[] customNodes = customValidationSetModel.getData();
+            processNodeModels(customNodes, arrayPathToSizeMap, jsonMap);
+        }
 
         return jsonMap;
     }
diff --git a/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExportTest.java b/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExportTest.java
index a64994d..1962feb 100644
--- a/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExportTest.java
+++ b/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/DeveloperMockExportTest.java
@@ -16,13 +16,13 @@
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
+import java.io.File;
 import java.io.IOException;
 import java.util.*;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.*;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.*;
 
 public class DeveloperMockExportTest {
 
@@ -33,6 +33,45 @@ public void resetDeveloperMockExport() {
         export = new DeveloperMockExport();
     }
 
+    @Test
+    public void getCoreValidationSetByItselfAndCustomValidationSet() throws Exception {
+
+        DeveloperMockExport exportMock = Mockito.spy(DeveloperMockExport.class);
+        doNothing().when(exportMock).writeDeveloperMock(Mockito.any(File.class), Mockito.anyString(), Mockito.anyString());
+
+        ValidationSetModel coreValidationSetModel = Mockito.mock(ValidationSetModel.class);
+        when(coreValidationSetModel.getValidationSetName()).thenReturn(ExportConstants.CORE_VALIDATION_SET);
+        when(coreValidationSetModel.getData()).thenReturn(new NodeModel[0]);
+
+        ValidationSetModel customValidationSetModel = Mockito.mock(ValidationSetModel.class);
+        when(customValidationSetModel.getValidationSetName()).thenReturn("FOO");
+        when(customValidationSetModel.getData()).thenReturn(new NodeModel[0]);
+
+        List<ValidationSetModel> validations = new ArrayList<>();
+        validations.add(coreValidationSetModel);
+        validations.add(customValidationSetModel);
+
+        exportMock.export(new File(System.getProperty("user.dir")), validations);
+        verify(exportMock, times(2)).writeDeveloperMock(Mockito.any(File.class), Mockito.anyString(), Mockito.anyString());
+    }
+
+    @Test
+    public void getCoreValidationSetByItself() throws Exception {
+
+        DeveloperMockExport exportMock = Mockito.spy(DeveloperMockExport.class);
+        doNothing().when(exportMock).writeDeveloperMock(Mockito.any(File.class), Mockito.anyString(), Mockito.anyString());
+
+        ValidationSetModel coreValidationSetModel = Mockito.mock(ValidationSetModel.class);
+        when(coreValidationSetModel.getValidationSetName()).thenReturn(ExportConstants.CORE_VALIDATION_SET);
+        when(coreValidationSetModel.getData()).thenReturn(new NodeModel[0]);
+
+        List<ValidationSetModel> validations = new ArrayList<>();
+        validations.add(coreValidationSetModel);
+
+        exportMock.export(new File(System.getProperty("user.dir")), validations);
+        verify(exportMock, times(1)).writeDeveloperMock(Mockito.any(File.class), Mockito.anyString(), Mockito.anyString());
+    }
+
     @Test
     public void getCoreValidationSet() throws IOException {
 
diff --git a/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessorTest.java b/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessorTest.java
index 2cdf479..7a83f6f 100644
--- a/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessorTest.java
+++ b/TMBuilder/src/test/java/com/ebay/tool/thinmodelgen/gui/menu/export/developer/mock/processor/JsonMapStructureProcessorTest.java
@@ -32,6 +32,38 @@ public class JsonMapStructureProcessorTest {
     private JsonMapStructureProcessor processor = new JsonMapStructureProcessor();
     private Gson gson = new GsonBuilder().serializeNulls().create();;
 
+    @Test
+    public void testGetJsonMapForValidationsCoreAndNullCustomValues() throws Exception {
+
+        JsonBooleanType jsonBooleanType = new JsonBooleanType("Foo");
+        jsonBooleanType.updateCheckForPath("$.foo.bar", new TMJPStringCheck());
+        String booleanSerializedType = JsonBaseTypePersistence.serialize(jsonBooleanType);
+
+        PathNode[] booleanPathNodes = new PathNode[4];
+        booleanPathNodes[0] = new PathNode("$", "class com.ebay.tool.thinmodelgen.jsonschema.type.JsonObjectType", 0);
+        booleanPathNodes[1] = new PathNode("foo", "class com.ebay.tool.thinmodelgen.jsonschema.type.JsonObjectType", 0);
+        booleanPathNodes[3] = new PathNode("bar", "class com.ebay.tool.thinmodelgen.jsonschema.type.JsonBooleanType", 0);
+
+        NodeModel booleanNodeModel = new NodeModel(booleanPathNodes, booleanSerializedType);
+        NodeModel[] coreNodeModel = new NodeModel[] {booleanNodeModel};
+        ValidationSetModel coreValidationSet = new ValidationSetModel("core", coreNodeModel);
+
+        TreeMap<String, Integer> treeMap = new TreeMap<>(new SmallestToLargestArrayPathComparator());
+
+        Map actualJsonMap = processor.getJsonMapForValidations(treeMap, coreValidationSet, null);
+
+        // Define expected
+        HashMap<String, Object> foo = new HashMap<>();
+        foo.put("bar", null);
+        HashMap<String, Object> expectedJsonMap = new HashMap<>();
+        expectedJsonMap.put("foo", foo);
+
+        String actual = gson.toJson(actualJsonMap);
+        String expected = gson.toJson(expectedJsonMap);
+
+        assertThat(actual, is(equalTo(expected)));
+    }
+
     @Test
     public void testGetJsonMapForValidationsCoreAndCustom() throws Exception {