XSLT fails when envelop is added - xslt

Question

I have a perfectly working XSL (thanks to you / StackOverflow):
https://xsltfiddle.liberty-development.net/3NgtZRc
Input xml
<Containers xmlns="https://www.uniconcreation.com/2021/IvenzaShippingContainer">
<Container>
<Name>INTERIEUR1</Name>
<Number>1</Number>
<SSCC>111</SSCC>
<SubContainers>
<Container>
<Id>I1371851</Id>
<SalesOrderNumber>2012231</SalesOrderNumber>
<ProductionOrderNumber>I2017658</ProductionOrderNumber>
<Name>ACCESSOIRE1</Name>
<Barcode>181001371851</Barcode>
<Items>
<Item>
<Id>I8709475</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<SalesOrderRowExternalReference>1</SalesOrderRowExternalReference>
<Quantity>1</Quantity>
</Item>
<Item>
<Id>I8709476</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<SalesOrderRowExternalReference>1</SalesOrderRowExternalReference>
<Quantity>1</Quantity>
</Item>
</Items>
</Container>
<Container>
<Id>I1371852</Id>
<SalesOrderNumber>2012231</SalesOrderNumber>
<ProductionOrderNumber>I2017658</ProductionOrderNumber>
<Name>PANEEL1</Name>
<Barcode>181001371852</Barcode>
<Items>
<Item>
<Id>I8709492</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<SalesOrderRowExternalReference>1</SalesOrderRowExternalReference>
<Quantity>1</Quantity>
</Item>
</Items>
</Container>
</SubContainers>
</Container>
XSL
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xpath-default-namespace="https://www.uniconcreation.com/2021/IvenzaShippingContainer" xmlns="https://www.uniconcreation.com/2021/IvenzaShippingContainer" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="Containers">
<xsl:variable name="sscc" select="Container/SSCC"/>
<xsl:copy>
<xsl:for-each select="//Container">
<xsl:variable name="level" select="count(ancestor::*)"/>
<xsl:choose>
<xsl:when test="$level = 1">
<xsl:copy>
<xsl:copy-of select="Id"/>
<xsl:copy-of select="SalesOrderNumber"/>
<xsl:copy-of select="ProductionOrderNumber"/>
<xsl:copy-of select="Name"/>
<xsl:copy-of select="Type"/>
<xsl:copy-of select="Number"/>
<xsl:copy-of select="SSCC"/>
<xsl:copy-of select="Barcode"/>
<xsl:copy-of select="StartedAt"/>
<xsl:copy-of select="CompletedAt"/>
<xsl:choose>
<xsl:when test="SubContainers">
<Items>
<xsl:for-each select="SubContainers">
<Item>
<Id>
<xsl:value-of select="Container[1]/Id"/>
</Id>
<SalesOrderRowId>
<xsl:value-of select="Container[1]/Items/Item[1]/SalesOrderRowId"/>
</SalesOrderRowId>
<Quantity>1</Quantity>
</Item>
</xsl:for-each>
</Items>
</xsl:when>
<xsl:otherwise>
<xsl:copy-of select="Items"/>
</xsl:otherwise>
</xsl:choose>
</xsl:copy>
</xsl:when>
<xsl:otherwise>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
Result
<?xml version="1.0" encoding="UTF-8"?>
<Containers xmlns="https://www.uniconcreation.com/2021/IvenzaShippingContainer">
<Container>
<Name>INTERIEUR1</Name>
<Number>1</Number>
<SSCC>111</SSCC>
<Items>
<Item>
<Id>I1371851</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<Quantity>1</Quantity>
</Item>
</Items>
</Container>
</Containers>
*Especially the xpath-default-namespace helped me preventing getting an empty xmlns="" for the Items Literal
But then I found out SAP PI puts an envelop around my message:
<?xml version="1.0" encoding="UTF-8"?>
<ns0:Messages xmlns:ns0="http://sap.com/xi/XI/SplitAndMerge">
<ns0:Message1>
<Containers xmlns="https://www.uniconcreation.com/2021/IvenzaShippingContainer">
<Container>
<Name>INTERIEUR1</Name>
<Number>1</Number>
<SSCC>111</SSCC>
<SubContainers>
<Container>
<Id>I1371851</Id>
<SalesOrderNumber>2012231</SalesOrderNumber>
<ProductionOrderNumber>I2017658</ProductionOrderNumber>
<Name>ACCESSOIRE1</Name>
<Barcode>181001371851</Barcode>
<Items>
<Item>
<Id>I8709475</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<SalesOrderRowExternalReference>1</SalesOrderRowExternalReference>
<Quantity>1</Quantity>
</Item>
<Item>
<Id>I8709476</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<SalesOrderRowExternalReference>1</SalesOrderRowExternalReference>
<Quantity>1</Quantity>
</Item>
</Items>
</Container>
<Container>
<Id>I1371852</Id>
<SalesOrderNumber>2012231</SalesOrderNumber>
<ProductionOrderNumber>I2017658</ProductionOrderNumber>
<Name>PANEEL1</Name>
<Barcode>181001371852</Barcode>
<Items>
<Item>
<Id>I8709492</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<SalesOrderRowExternalReference>1</SalesOrderRowExternalReference>
<Quantity>1</Quantity>
</Item>
</Items>
</Container>
</SubContainers>
</Container>
</Containers>
</ns0:Message1>
</ns0:Messages>
And I ended up with this:
<?xml version="1.0" encoding="UTF-8"?>
<Containers xmlns="https://www.uniconcreation.com/2021/IvenzaShippingContainer"
xmlns:ns0="http://sap.com/xi/XI/SplitAndMerge"/>
I tried prefixing all namespaces but I hope there's another way :(
Required output
<?xml version="1.0" encoding="UTF-8"?>
<ns0:Messages xmlns:ns0="http://sap.com/xi/XI/SplitAndMerge">
<ns0:Message1>
<Containers xmlns="https://www.uniconcreation.com/2021/IvenzaShippingContainer">
<Container>
<Name>INTERIEUR1</Name>
<Number>1</Number>
<SSCC>111</SSCC>
<Items>
<Item>
<Id>I1371851</Id>
<SalesOrderRowId>I671068</SalesOrderRowId>
<Quantity>1</Quantity>
</Item>
</Items>
</Container>
</Containers>
</ns0:Message1>
</ns0:Messages>
Kind regards,
Mike

Answer 1

With two wrapper elements, the value of <xsl:variable name="level" select="count(ancestor::*)"/> is going to change so perhaps your check <xsl:when test="$level = 1"> needs to be converted to <xsl:when test="$level = 3">.
You will also need to add some identity template to make sure the wrapper elements are copied.