How to escape variable interpolation?

[David Hoffer]

I have a case where I have a text file that is generated with a hard coded
string and I would like to replace that with Maven variables, but I want
the literal variable string to go in the file not the interpolated values.

I read http://maven.apache.org/shared/maven-filtering/ that i should be
able to do this with a leading \ but that doesn't work.  It still
resolves ${service.root.url}.

<execution>
    <id>replace-namespace</id>
    <phase>generate-resources</phase>
    <goals>
        <goal>run</goal>
    </goals>
    <configuration>
        <failOnError>true</failOnError>
        <target>
            <replace
dir="${project.build.directory}/generated-resources/META-INF/" token="
http://jmsappsvr/bullpen/service";
value="\${service.root.url}/bullpen/readwrite" >
                <include name="**/*.wsdl" />
            </replace>
        </target>
    </configuration>
</execution>

How can this be done?

-Dave