I'm using the below filter in Connect Client and get an org.xml.sax.SAXParseException: Content is not allowed in prolog error.
<quer:filtering xmlns:quer="http://www.taleo.com/ws/integration/query">
<quer:notEqual>
<quer:projection alias="TestSubStr">
<quer:substring>
<quer:field path="Credentials,SSOID"/>
<quer:integer>8</quer:integer>
<quer:integer>6</quer:integer>
</quer:substring>
</quer:projection>
<quer:string>wlgore</quer:string>
</quer:notEqual>
</quer:filtering>
The "projection" is not needed in that context. If your projectedClass is "Candidate", the following filter should work:
If your projectClass is "Application", you need to adjust the path of the SSOID field: