Add EMPTY_ELEMENT_AS_EMPTY_ARRAY Feature

Author: Croway

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/FromXmlParser.java

@@ -86,6 +86,19 @@ public enum Feature implements FormatFeature
          */
         EMPTY_ELEMENT_AS_NULL(false),
 
+        /**
+         * Feature that indicates whether XML Empty elements (ones where there are
+         * no separate start and end tags, but just one tag that ends with "/>")
+         * are exposed as {@link JsonToken#START_ARRAY} {@link JsonToken#END_ARRAY}) or not. If they are not
+         * returned as `[]` tokens, they will be returned as {@link JsonToken#VALUE_STRING}
+         * tokens with textual value of "" (empty String).
+         *<p>
+         * Default setting is {@code false}
+         *
+         * @since 2.9
+         */
+        EMPTY_ELEMENT_AS_EMPTY_ARRAY(false),
+
         /**
          * Feature that indicates whether XML Schema Instance attribute
          * {@code xsi:nil} will be processed automatically -- to indicate {@code null}

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlTokenStream.java

@@ -5,6 +5,7 @@
 import javax.xml.XMLConstants;
 import javax.xml.stream.*;
 
+import com.fasterxml.jackson.core.JsonToken;
 import org.codehaus.stax2.XMLStreamLocation2;
 import org.codehaus.stax2.XMLStreamReader2;
 
@@ -549,6 +550,7 @@ private final int _next() throws XMLStreamException
 
     /**
      * @return Collected text, if any, EXCEPT that if {@code FromXmlParser.Feature.EMPTY_ELEMENT_AS_NULL}
+     *    OR {@code FromXmlParser.Feature.EMPTY_ELEMENT_AS_EMPTY_ARRAY}
      *    AND empty element, returns {@code null}
      */
     private final String _collectUntilTag() throws XMLStreamException
@@ -559,6 +561,9 @@ private final String _collectUntilTag() throws XMLStreamException
             if (FromXmlParser.Feature.EMPTY_ELEMENT_AS_NULL.enabledIn(_formatFeatures)) {
                 return null;
             }
+            if (FromXmlParser.Feature.EMPTY_ELEMENT_AS_EMPTY_ARRAY.enabledIn(_formatFeatures)) {
+                return JsonToken.START_ARRAY.asString() + JsonToken.END_ARRAY.asString();
+            }
             return "";
         }
 

src/test/java/com/fasterxml/jackson/dataformat/xml/deser/EmptyStringValueTest.java

@@ -85,6 +85,26 @@ public void testEmptyElement() throws Exception
         assertEquals("", name.last);
     }
 
+    public void testEmptyElementEmptyArray() throws Exception
+    {
+        final String XML = "<name><first/><last></last></name>";
+
+        // Default settings (since 2.12): empty element does NOT become `null`:
+        Name name = MAPPER.readValue(XML, Name.class);
+        assertNotNull(name);
+        assertEquals("", name.first);
+        assertEquals("", name.last);
+
+        // but can be changed
+        XmlMapper mapper2 = XmlMapper.builder()
+                .enable(FromXmlParser.Feature.EMPTY_ELEMENT_AS_EMPTY_ARRAY)
+                .build();
+        name = mapper2.readValue(XML, Name.class);
+        assertNotNull(name);
+        assertEquals("[]", name.first);
+        assertEquals("", name.last);
+    }
+
     public void testEmptyStringElement() throws Exception
     {
         // then with empty element