currently we can configure TransformerFactory used by saxon by specifying features/attributes there. However, this can only take effect on an XML parser that Saxon creates. It has no effect if camel application creates the XML parser (that is, if the input is supplied to Saxon as a Source object)
So we need to saxonReaderProperties option to camel-xslt-saxon endpoint, if saxonReaderProperties isn't null, create a XMLReader and specify features on it, so that we can gain fully control of xml parsed used by saxon. This is important to prevent XXE attack when using saxon to do xslt transform. Like by disabling uri=http://xml.org/sax/features/external-general-entities" to not access sensitive local files.