Camel transformer using inconsistent sources

Issue

Using the following camel route:

<camel:process ref="serviceProcessor" />
<camel:marshal>
    <camel:jaxb ... />
</camel:marshal>
<camel:to uri="log:AFTER-MARSHAL" />
<camel:to uri="xslt:xslt/response.xsl?transformerFactory=saxonTransformerFactory" pattern="InOut" />

I see that my XSLT transformation are using different types:

XsltBuilder                    TRACE Using javax.xml.transform.dom.DOMSource@a353ed as source
XsltBuilder                    TRACE Using javax.xml.transform.stax.StAXSource@555538 as source
XsltBuilder                    TRACE Using javax.xml.transform.stream.StreamSource@1421ab0 as source
XsltBuilder                    TRACE Using javax.xml.transform.sax.SAXSource@141f9f6 as source

Why are the different types used? How does camel decides which type to use when converting from byte[]? Why sometimes StAXSource is used if by default allowStAX=false in camel-xslt component?