Sync with underscore-java.

Author: javadev

src/main/java/com/github/underscore/lodash/U.java

@@ -99,7 +99,8 @@ public enum Mode {
         REPLACE_EMPTY_VALUE_WITH_NULL,
         FORCE_ATTRIBUTE_USAGE,
         DEFINE_ROOT_NAME,
-        FORCE_ATTRIBUTE_USAGE_AND_DEFINE_ROOT_NAME
+        FORCE_ATTRIBUTE_USAGE_AND_DEFINE_ROOT_NAME,
+        REPLACE_NULL_WITH_EMPTY_VALUE
     }
 
     public U(final Iterable<T> iterable) {
@@ -2253,6 +2254,8 @@ public static String jsonToXml(String json, Xml.XmlStringBuilder.Step identStep,
                 result = Xml.toXml((Map) object, identStep, newRootName);
             } else if (mode == Mode.FORCE_ATTRIBUTE_USAGE_AND_DEFINE_ROOT_NAME) {
                 result = Xml.toXml(forceAttributeUsage((Map) object), identStep, newRootName);
+            } else if (mode == Mode.REPLACE_NULL_WITH_EMPTY_VALUE) {
+                result = Xml.toXml(replaceNullWithEmptyValue((Map) object), identStep, newRootName);
             } else {
                 result = Xml.toXml((Map) object, identStep);
             }
@@ -2496,6 +2499,33 @@ private static Object makeAttributeUsage(Object value) {
         return result;
     }
 
+    @SuppressWarnings("unchecked")
+    public static Map<String, Object> replaceNullWithEmptyValue(Map<String, Object> map) {
+        Map<String, Object> outMap = newLinkedHashMap();
+        for (Map.Entry<String, Object> entry : map.entrySet()) {
+            outMap.put(entry.getKey(), entry.getValue() == null ? newLinkedHashMap() :
+                makeReplaceNullValue(entry.getValue()));
+        }
+        return outMap;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static Object makeReplaceNullValue(Object value) {
+        final Object result;
+        if (value instanceof List) {
+            List<Object> values = newArrayList();
+            for (Object item : (List) value) {
+                values.add(item instanceof Map ? replaceNullWithEmptyValue((Map) item) : item);
+            }
+            result = values;
+        } else if (value instanceof Map) {
+            result = replaceNullWithEmptyValue((Map) value);
+        } else {
+            result = value;
+        }
+        return result;
+    }
+
     public static long gcd(long value1, long value2) {
         if (value1 == 0) {
             return value2;

src/test/java/com/github/underscore/lodash/LodashTest.java

@@ -762,6 +762,10 @@ public void formatXml() {
             U.formatXml("<a>\n  <b></b>\n  <b></b>\n</a>", Xml.XmlStringBuilder.Step.TABS));
         assertEquals("<a number=\"true\">1.00</a>", U.formatXml("<a number=\"true\">1.00</a>"));
         assertEquals("<a number=\"true\">2.01</a>", U.formatXml("<a number=\"true\">2.01</a>"));
+    }
+
+    @Test
+    public void forceAttributeUsage() {
         assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
                 + "<RootElm>\n"
                 + "  <author DOB=\"\" EMailID=\"\" PlaceId=\"\" SSN=\"\">\n"
@@ -793,6 +797,34 @@ public void formatXml() {
         U.forceAttributeUsage(map2);
     }
 
+    @Test
+    public void replaceNullWithEmptyValue() {
+        assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+                + "<RootElm>\n"
+                + "  <author>\n"
+                + "    <DOB></DOB>\n"
+                + "    <value string=\"true\"/>\n"
+                + "  </author>\n"
+                + "</RootElm>", U.jsonToXml("{\n"
+                + "  \"RootElm\": {\n"
+                + "    \"author\": {\n"
+                + "      \"DOB\": null,\n"
+                + "      \"value\": \"\"\n"
+                + "    }\n"
+                + "  }\n"
+                + "}", U.Mode.REPLACE_NULL_WITH_EMPTY_VALUE));
+        Map<String, Object> map = U.newLinkedHashMap();
+        List<Object> list = U.newArrayList();
+        list.add(U.newLinkedHashMap());
+        map.put("list", list);
+        U.replaceNullWithEmptyValue(map);
+        Map<String, Object> map2 = U.newLinkedHashMap();
+        List<Object> list2 = U.newArrayList();
+        list2.add(U.newArrayList());
+        map2.put("list", list2);
+        U.replaceNullWithEmptyValue(map2);
+    }
+
     @Test
     public void changeXmlEncoding() {
         assertEquals("<?xml version=\"1.0\" encoding=\"windows-1251\"?>\n<a>Test</a>",