Default transform factory of saxon has been switched to Xalan in later releases.

Description:

When there is an XSLT mediator in the mediation sequence we can observe the below ERROR while invoking that API.

TID: [36] [] [2021-06-08 21:41:47,551] ERROR {org.apache.synapse.mediators.transform.XSLTMediator} - Fatal error occurred in stylesheet parsing. ; Line#: 91; Column#: 60
javax.xml.transform.TransformerException: Could not find function: ends-with
        at org.apache.xpath.compiler.XPathParser.error(XPathParser.java:610)
        at org.apache.xpath.compiler.XPathParser.FunctionCall(XPathParser.java:1507)
        at org.apache.xpath.compiler.XPathParser.PrimaryExpr(XPathParser.java:1446)

This was working fine in APIM 2.6.0. (when trying this out locally in APIM 2.6.0 there was no ERROR) But when trying this out locally with APIM 3.2.0 or APIM 4.0.0 we can observe the same behavior.

When further analyzing I was able to identify that if we remove the wso2am-3.2.0/lib/xalan-2.7.2.wso2v2.jar and try invoking the same API it won't prompt any ERRORs. (Works as expected) This xalan-2.7.2 JAR is not in APIM 2.6.0 version.

We were able to resolve this issue by adding the below system parameter to startup script.
-Djavax.xml.transform.TransformerFactory=net.sf.saxon.TransformerFactoryImpl \

Affected Product Version:

APIM 3.2, APIM 4.0

Start with the APIM 3.2.0 and 4.0.0 behavior described in the report, including the startup script and the xalan-2.7.2.wso2v2.jar reference. Confirm whether the documentation should cover the TransformerFactory system parameter workaround; done means the affected versions and workaround are clearly documented.