FileBackedAttributeFilter

[Rod Widdowson]

>    <bean id="FileBackedAttributeFilter"
>          class="net.shibboleth.ext.spring.resource.FileBackedHTTPResource"
>          c:url="https://example.com/idp/attribute-filter.xml"
>          c:backingFile="%{idp.home}/conf/attribute-filter.dwn.xml">
>    </bean>

You need a 

c:client-ref="shibboleth.MemoryCachingHttpClient" 
              
or a 

c:client-ref="shibboleth.FileCachingHttpClient" 

in there.  The version of services.xml that is shipped contains an example in the comments.

/Rod