Generate xml map serialization

tools/code-generation/generator/src/main/resources/com/amazonaws/util/awsclientgenerator/velocity/cpp/xml/ModelClassMemberSingleXmlizeSource.vm

@@ -63,8 +63,33 @@ ${memberVarName}##
 #serializeXmlPayloadElement($listSpaces, $listElSerializationName, $lowerCaseVarName, $member.shape.listMember, "item", $listElParentNode)
   ${spaces}}
 #end##macro serializeXmlListPayloadElement
+##-------------------- serializeXmlMapPayloadElement macro
+#macro( serializeXmlMapPayloadElement $spaces $serializationName $lowerCaseVarName $member $memberVarName )
+##https://smithy.io/2.0/spec/protocol-traits.html#xml-map-serialization
+##TODO: might not be 100% correct, pending validation by protocol tests
+##// /* --- the actual shape member is $member; the actual shape is $member.shape; --- */
+##// /* --- key member: ${member.shape.mapKey} */
+##// /* --- key shape: ${member.shape.mapKey.shape} */
+##// /* --- key member: ${member.shape.mapValue} */
+##// /* --- key shape: ${member.shape.mapValue.shape} */
+#set($mapEntryParentNode = "parentNode")
+#if(!($member.locationName && $member.shape.flattened))
+  ${spaces}XmlNode ${lowerCaseVarName}ParentNode = parentNode.CreateChildElement("${serializationName}");
+#set($mapEntryParentNode = "${lowerCaseVarName}ParentNode")
+#end
+  ${spaces}for(const auto& mapItem : $memberVarName)
+  ${spaces}{
+#set($mapSpaces = $spaces + "  ")
+#set($mapEntrySerializationName = "#if($member.locationName)$member.locationName#{else}entry#end")
+  ${spaces}  XmlNode ${lowerCaseVarName}MapEntryNode = ${mapEntryParentNode}.CreateChildElement("${mapEntrySerializationName}");
+#set($mapKeySerializationName = "#if($member.shape.mapKey.locationName)$member.shape.mapKey.locationName#{else}key#end")
+#serializeXmlPayloadElement($mapSpaces, $mapKeySerializationName, "${lowerCaseVarName}Key", $member.shape.mapKey, "mapItem.first", "${lowerCaseVarName}MapEntryNode")
+#set($mapValueSerializationName = "#if($member.shape.mapValue.locationName)$member.shape.mapValue.locationName#{else}value#end")
+#serializeXmlPayloadElement($mapSpaces, $mapValueSerializationName, "${lowerCaseVarName}Value", $member.shape.mapValue, "mapItem.second", "${lowerCaseVarName}MapEntryNode")
+  ${spaces}}
+#end##macro serializeXmlMapPayloadElement
 ##-------------------- END OF MACROS, ACTUAL TEMPLATE BEGINS --------------------
-#if($member.shape.enum || $member.shape.boolean || $member.shape.primitive || $member.shape.timeStamp || $member.shape.structure)
+#if($member.shape.enum || $member.shape.boolean || $member.shape.primitive || $member.shape.timeStamp || $member.shape.structure || $member.shape.blob)
 #serializeXmlPayloadElement($spaces, $serializationName, $lowerCaseVarName, $member, $memberVarName)
 #elseif($member.shape.string)
 #if($member.xmlAttribute)
@@ -101,7 +126,7 @@ ${memberVarName}##
 #elseif($member.shape.list)
 #serializeXmlListPayloadElement($spaces, $serializationName, $lowerCaseVarName, $member, $memberVarName)
 #elseif($member.shape.map)
-!!!! Work in progress for map serialization
+#serializeXmlMapPayloadElement($spaces, $serializationName, $lowerCaseVarName, $member, $memberVarName)
 #else
 !!!! Code generation error: the template does not support this shape under $serializationName serialization to xml: ${member}
 #end##End of member.shape is structure or list