In Java , no TransformerException is thrown while performing XSLT transformation when I send a bad XML ( XML with no tags mentioned in XSLT)

In Java , while transforming one XML into another XML using an XSLT file , when given a bad XML as input ( negative testing) no TransformerException is thrown.

Bad XML here is an XML with no tags which XSLT expects
Example of Bad XML
<Sample>123</Sample>

XSLT snapshot ( Note Sample is not a tag specified anywhere here )

 *<xsl:template match="/SammpleReply" xpath-default-namespace="SammpleReply" exclude-result-prefixes="#all">
       <RadialReply xmlns="http://SammpleReply.com">
            <xsl:choose>
                <xsl:when test="PaymentContextBase">
                   <PaymentContextBase>
                       <OrderId><xsl:value-of select="RadialReply/Radial:RadialReplySessionId"/></OrderId>
                   </PaymentContextBase>
                   <TenderType><xsl:value-of select="RadialReply/Radial:TenderType"/></TenderType>
                </xsl:when>
               <xsl:otherwise>
                    <RadialReplyContext>
                        <OrderId><xsl:value-of select="RadialContext/payment:RadialUniqueId"/></OrderId>
                         <xsl:element name="RadialUniqueId" >
                            <xsl:attribute name="isToken"><xsl:value-of select="RadialContext/payment:PaymentAccountUniqueId/@isToken"/></xsl:attribute>
                            <xsl:value-of select="RadialContext/payment:RadialUniqueId"/>
                         </xsl:element>
                    </RadialReplyContext>
                   <TenderType><xsl:value-of select="PaymentContext/payment:TenderType"/></TenderType>
               </xsl:otherwise>
            </xsl:choose>
            <SlotsAvailable><xsl:value-of select="SlotsAvailability"/></SlotsAvailable>
           <xsl:choose>
                <xsl:when test="Reattempt">
                    <ReauthorizationAttempted><xsl:value-of select="ReattemptValue"/></ReauthorizationAttempted>
                </xsl:when>
           </xsl:choose>
       </RadialReply>*

Input

<Sample>202008131228</Sample>

Output

<?xml version="1.0" encoding="UTF-8"?>202008131228

Desired Result : If an incoming XML does not have any XML element defined in XSLT . Exception should be thrown ( Which is not happening ) Need to know why and I want the code to throw an exception in this case . What code logic would achieve that ?
Code just loads the XSLT File and transforms it . Code does not go to exception block. it transforms successfully and String outputResultStr is the output above

 Reader xmlReader = new StringReader(payloadStr);
                StringWriter stringWriter = new StringWriter();
                Result result = new StreamResult(stringWriter);
                transformer.transform(new StreamSource(xmlReader), result);
                outputResultStr = stringWriter.toString();
                

            } catch (TransformerException trEx) {
                  } 

In XSLT 1.0 or 2.0, add a template rule

<xsl:template match="*">
  <xsl:message terminate="yes">Unknown element <xsl:value-of select="name()"/></xsl:message>
</xsl:template>

to match elements that are not matched by any other template rule.

In 3.0, add <xsl:mode on-no-match="fail"/>.

The reason it's not failing is that XSLT defines a default template rule to process elements that are not matched by any other template rule in the stylesheet.

xsl transform will pass even if there are no matching tags.

There are several options ...

• refactor xsl to match / and look for desired/allowed tags and throw error using <xsl:message terminate="yes"/> if not found
• create xml schema for input xml an validate before transform

You can implement SAX schema validation API before XSLT transformation.

> Here my SAX validation program specifies the schema to validate XML input data:

	SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);

	InputSourceHandle saxHandle = new InputSourceHandle();
	
	saxHandle.setErrorHandler(new InputSourceHandle.DraconianErrorHandler());
		    
	String procSchema =
	      "<?xml version='1.0' encoding='UTF-8'?>" +
	      "<xs:schema xmlns:xs='http://www.w3.org/2001/XMLSchema' " +
	          "xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' " +
	          "xsi:schemaLocation='http://www.w3.org/2001/XMLSchema XMLSchema.xsd'>" +
	        "<xs:element name='ProcedureDocument'>" +
	          "<xs:complexType mixed='true'>" +
	            "<xs:choice minOccurs='0' maxOccurs='unbounded'>" +
	              "<xs:element name='title'/>" +
	              "<xs:element name='confidentialityCode'/>" +
	              "<xs:element name='originalText'/>" +
	              "<xs:element name='statusCode'/>" +		              
	              "<xs:element name='methodCode'/>" +
	              "<xs:element name='reference'/>" +
	            "</xs:choice>" +
	            "<xs:attribute name=\"value\" type='xs:string' use='optional'/>" +
	          "</xs:complexType>" +
	        "</xs:element>" +
	      "</xs:schema>";

	Schema schema = factory.newSchema(new StreamSource(new StringReader(procSchema)));

saxHandle.setDefaultWriteSchema(schema);
…….
//proceed XSLT transformation

> A well-formed and valid XML file is:

<?xml version="1.0" encoding="utf-8"?>
</ProcedureDocument>
	<title>Procedures Anesthesia</title>
	<confidentialityCode>Confidential</confidentialityCode>
	<originalText>Cardiac Surgery :: CABG, arterial, three</originalText>
	<statusCode code="performed"/>
	<methodCode>UNK</methodCode>
	<reference value="#Procedure2"/>
</ProcedureDocument>

Just one validation can precisely catch all range of erroneous input and exit the application gracefully.
> e.g: missing tag </ProcedureDocument>

Error 
   Error reported by XML parser processing null: cvc-elt.1: Cannot find the declaration of
  element 'title'.: cvc-elt.1: Cannot find the declaration of element 'title'.

> e.g: ill-formed element/attribute => <reference Value="#Procedure2"/>

Error 
   Error reported by XML parser processing null: The markup in the document preceding the
  root element must be well-formed.: The markup in the document preceding the root element
  must be well-formed.

> e.g: ill-formed xpath/tag =>

ProcedureDocument
	<title>Procedures Anesthesia</title>

Error 
   Error reported by XML parser processing null: Content is not allowed in prolog.: Content
  is not allowed in prolog.