Export GeoPackge fails due to mis-matched end-tags in XML

[emxsys]

After the upgrade to GeoServer 2.13, the export GeoPackage process generates a valid XML, but somewhere in the process, the XML end-tags end up with ":" chars injected into the end-tags.
For example: <layers>...</:layers>

Error text:

<wps:ExecuteResponse xml:lang="en" service="WPS" serviceInstance="http://cobra:8080/geoserver/ows?" version="1.0.0">
  <wps:Process wps:processVersion="1.0.0">
    <ows:Identifier>gs:GeoPackage</ows:Identifier><ows:Title>GeoPackage</ows:Title>
    <ows:Abstract>Geopackage Process</ows:Abstract>
  </wps:Process>
  <wps:Status creationTime="2018-06-26T23:07:14.003Z">
    <wps:ProcessFailed>
      <ows:ExceptionReport version="1.1.0">
        <ows:Exception exceptionCode="NoApplicableCode">
          <ows:ExceptionText>Failed to retrieve value for input contents
The element type &quot;layers&quot; must be terminated by the matching end-tag &quot;&lt;/layers&gt;&quot;.
          </ows:ExceptionText>
        </ows:Exception>
      </ows:ExceptionReport>
    </wps:ProcessFailed>
  </wps:Status>
</wps:ExecuteResponse>

[emxsys]

Example

Here is the XML for exporting a GeoPackage. Note the embedded colon chars in the layers and srs tags.

<?xml version="1.0" encoding="UTF-8"?><wps:Execute version="1.0.0" service="WPS" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.opengis.net/wps/1.0.0" xmlns:wfs="http://www.opengis.net/wfs" xmlns:wps="http://www.opengis.net/wps/1.0.0" xmlns:ows="http://www.opengis.net/ows/1.1" xmlns:gml="http://www.opengis.net/gml" xmlns:ogc="http://www.opengis.net/ogc" xmlns:wcs="http://www.opengis.net/wcs/1.1.1" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.opengis.net/wps/1.0.0 http://schemas.opengis.net/wps/1.0.0/wpsAll.xsd">
  <ows:Identifier>gs:GeoPackage</ows:Identifier>
  <wps:DataInputs>
    <wps:Input>
      <ows:Identifier>contents</ows:Identifier>
      <wps:Data>
        <wps:ComplexData mimeType="text/xml; subtype=geoserver/geopackage">
          <geopackage xmlns="http://www.opengis.net/gpkg" name="world">
            <tiles name="world">
              <layers>test:world</layers>
              <styles>raster</styles>
              <transparent>false</transparent>
              <bbox>
                <minx>-180.0</minx>
                <miny>-90.0</miny>
                <maxx>180.0</maxx>
                <maxy>90.0</maxy>
              </bbox>
              <srs>EPSG:4326</srs>
              <coverage>
                <minZoom>0</minZoom>
                <maxZoom>8</maxZoom>
              </coverage>
            </tiles>
          </geopackage>
        </wps:ComplexData>
      </wps:Data>
    </wps:Input>
  </wps:DataInputs>
  <wps:ResponseForm>
    <wps:RawDataOutput>
      <ows:Identifier>geopackage</ows:Identifier>
    </wps:RawDataOutput>
  </wps:ResponseForm>
</wps:Execute>

Problem

GeoPackageProcessRequestPPIO.decode receives the following input (note the ":" in the end-tags after the layers tag.

input = (java.lang.String) "<geopackage name="world" xmlns:wfs='http://www.opengis.net/wfs' xmlns:xml='http://www.w3.org/XML/1998/namespace' xmlns:wcs='http://www.opengis.net/wcs/1.1.1' xmlns:gml='http://www.opengis.net/gml' xmlns:ows='http://www.opengis.net/ows/1.1' xmlns:ogc='http://www.opengis.net/ogc' xmlns:wps='http://www.opengis.net/wps/1.0.0' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xlink='http://www.w3.org/1999/xlink'>
            <tiles name="world">
              <layers>test:world</:layers>
              <styles>raster</:styles>
              <transparent>false</:transparent>
              <bbox>
                <minx>-180.0</:minx>
                <miny>-90.0</:miny>
                <maxx>180.0</:maxx>
                <maxy>90.0</:maxy>
              </:bbox>
              <srs>EPSG:4326</:srs>
              <coverage>
                <minZoom>0</:minZoom>
                <maxZoom>8</:maxZoom>
              </:coverage>
            </:tile...

[emxsys]

More Info

Upon further review, the it seems all the closing end-tags have an embedded colon. In a debugging hack, i simply replaced the </: string with </ in GeoPackageProcessRequestPPIO.decode and that allows the export process to proceed, only to generate this error:

gs:GeoPackageGeoPackageGeopackage ProcessFailed to retrieve value for input contents 
Errors were encountered while parsing GeoPackage contents: 
[org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 422; 
cvc-elt.1: Cannot find the declaration of element 'geopackage'.]

I would appear the entity resolver registered in applicationContext.xml cannot be found or was not loaded.