"entry key="signaturePropFile" value="file:/opt/file.txt"/>"

bean class="CustomResourceLoader" id="BPJcustomResourceLoader">
        property name="resource">
        value>file:/opt/file.txt</value>
        /property>
        /bean>
        entry key="signaturePropFile" value-ref="BPJcustomResourceLoader"/>

CustomResourceLoader cannot be cast to java.lang.String