Add new ElementWrappable marker interface

Author: cowtowncoder

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

@@ -0,0 +1,29 @@
+package com.fasterxml.jackson.dataformat.xml.deser;
+
+import java.util.Set;
+
+/**
+ * Minimal API to be implemented by XML-backed parsers for which "virtual"
+ * wrapping may be imposed.
+ *<p>
+ * NOTE: this method is considered part of internal implementation
+ * interface, and it is <b>NOT</b> guaranteed to remain unchanged
+ * between minor versions (it is however expected not to change in
+ * patch versions). So if you have to use it, be prepared for
+ * possible additional work.
+ *
+ * @since 2.15
+ */
+public interface ElementWrappable
+{
+    /**
+     * Method that may be called to indicate that specified names
+     * (only local parts retained currently: this may be changed in
+     * future) should be considered "auto-wrapping", meaning that
+     * they will be doubled to contain two opening elements, two
+     * matching closing elements. This is needed for supporting
+     * handling of so-called "unwrapped" array types, something
+     * XML mappings like JAXB often use.
+     */
+    public void addVirtualWrapping(Set<String> namesToWrap0, boolean caseInsensitive);
+}

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

@@ -29,6 +29,7 @@
  */
 public class FromXmlParser
     extends ParserMinimalBase
+    implements ElementWrappable // @since 2.15
 {
     /**
      * The default name placeholder for XML text segments is empty
@@ -431,27 +432,11 @@ public XMLStreamReader getStaxReader() {
 
     /*
     /**********************************************************
-    /* Internal API
+    /* ElementWrappable implementation
     /**********************************************************
      */
 
-    /**
-     * Method that may be called to indicate that specified names
-     * (only local parts retained currently: this may be changed in
-     * future) should be considered "auto-wrapping", meaning that
-     * they will be doubled to contain two opening elements, two
-     * matching closing elements. This is needed for supporting
-     * handling of so-called "unwrapped" array types, something
-     * XML mappings like JAXB often use.
-     *<p>
-     * NOTE: this method is considered part of internal implementation
-     * interface, and it is <b>NOT</b> guaranteed to remain unchanged
-     * between minor versions (it is however expected not to change in
-     * patch versions). So if you have to use it, be prepared for
-     * possible additional work.
-     * 
-     * @since 2.12
-     */
+    @Override
     public void addVirtualWrapping(Set<String> namesToWrap0, boolean caseInsensitive)
     {
 //System.out.printf("addVirtualWrapping(%s) at '%s' [case-insensitive? %s]\n", namesToWrap0, _parsingContext.pathAsPointer(), caseInsensitive);

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

@@ -154,7 +154,7 @@ protected final void _configureParser(JsonParser p) throws IOException
         while (p instanceof JsonParserDelegate) {
             p = ((JsonParserDelegate) p).delegate();
         }
-        if ((p instanceof FromXmlParser) && (_namesToWrap != null)) {
+        if ((p instanceof ElementWrappable) && (_namesToWrap != null)) {
             // 03-May-2021, tatu: as per [dataformat-xml#469] there are special
             //   cases where we get String token to represent XML empty element.
             //   If so, need to refrain from adding wrapping as that would
@@ -166,7 +166,7 @@ protected final void _configureParser(JsonParser p) throws IOException
                     //    is consumed during buffering, so need to consider that too
                     //    it seems (just hope we are at correct level and not off by one...)
                     || t == JsonToken.FIELD_NAME) {
-                ((FromXmlParser) p).addVirtualWrapping(_namesToWrap, _caseInsensitive);
+                ((ElementWrappable) p).addVirtualWrapping(_namesToWrap, _caseInsensitive);
             }
         }
     }