LPS-46799 StructureXsdException occurs after upgrading to 6.2 during the export/import process

Hi Marcellus,

after upgrading from 6.1 to 6.2 some of the auto generated  DDM structures became invalid. 
Exporting/importing these structures would fail, as the validation throws StructureXsdException  while the portal tries to create the new sturctures.

Here is a piece of the Data Definition called "Events" on 6.1.

```
 	<dynamic-element dataType="file-upload" fieldNamespace="ddm" name="attachment" type="ddm-fileupload">
 		<meta-data locale="en_US">
 			<entry name="acceptFiles"><![CDATA[*]]></entry>
 			<entry name="folder"><![CDATA[{"folderId":0,"folderName":"Documents Home"}]]></entry>
 			<entry name="label"><![CDATA[Attachment]]></entry>
 			<entry name="name"><![CDATA[attachment]]></entry>
 			<entry name="predefinedValue"><![CDATA[]]></entry>
 			<entry name="required"><![CDATA[false]]></entry>
 			<entry name="showLabel"><![CDATA[true]]></entry>
 			<entry name="tip"><![CDATA[Upload documents no larger than 3,000k.]]></entry>
 			<entry name="type"><![CDATA[ddm-fileupload]]></entry>
 		</meta-data>
 	</dynamic-element>
```
After the upgrade process have finished, it looks like the following:
```
 	<dynamic-element dataType="document-library" fieldNamespace="ddm" name="attachment" type="ddm-documentlibrary" required="false" showLabel="true">
 		<meta-data locale="en_US">
 			<entry name="folder"><![CDATA[{"folderId":0,"folderName":"Documents Home"}]]></entry>
 			<entry name="label"><![CDATA[Attachment]]></entry>
 			<entry name="name"><![CDATA[attachment]]></entry>
 			<entry name="predefinedValue"><![CDATA[]]></entry>
 			<entry name="tip"><![CDATA[Upload documents no larger than 3,000k.]]></entry>
 			<entry name="type"><![CDATA[ddm-fileupload]]></entry>
 		</meta-data>
 	</dynamic-element>
```

However, some invalid attributes still remain  in the xml: "folder", "name", "type"

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