mustRevalidate in cache apim policy not working - azure

Question

I am trying to implement cache remove in the policy . When i am testing it , i am getting one response as false where as i must receive it true
I am passing the header in the test section as : Cache-Control = maxAge & maxAge= 0
I am getting mustRevalidate as false where as i should receive it as true and perform cache-remove-value part . I have pasted the image also .
What exactly am i missing in policy ?
<policies>
<inbound>
<rewrite-uri template="#{
return ("/api/todo");
}" />
<set-header name="Cache-Control" exists-action="override">
<value>public, maxAge=3600</value>
</set-header>
<choose>
<when condition="#(context.Variables.GetValueOrDefault<string>("maxAge") != "0")">
<cache-lookup vary-by-developer="false" vary-by-developer-groups="false" downstream-caching-type="none" must-revalidate="true" caching-type="internal">
<vary-by-header>Accept</vary-by-header>
<vary-by-header>Accept-Charset</vary-by-header>
<vary-by-header>Accept-Encoding</vary-by-header>
<vary-by-header>Accept-Language</vary-by-header>
</cache-lookup>
</when>
</choose>
<set-variable name="cacheKey" value="#(context.Request.Headers["maxAge"].FirstOrDefault())" />
<set-variable name="mustRevalidate" value="#(context.Request.Headers.GetValueOrDefault("Cache-Control","").Contains("maxAge"))" />
<choose>
<when condition="#(context.Variables.GetValueOrDefault<bool>("mustRevalidate") == true)">
<cache-remove-value key="#(context.Variables.GetValueOrDefault<string>("cacheKey"))" />
</when>
</choose>
<cache-lookup-value key="#(context.Variables.GetValueOrDefault<string>("cacheKey"))" variable-name="cachedResponse" />
</inbound>
<backend>
<forward-request timeout="100" />
</backend>
<outbound>
<cache-store caching-mode="cache-on" duration="60" />
<cache-store-value key="#(context.Variables.GetValueOrDefault<string>("cacheKey"))" value="cacheKey" duration="60" />
</outbound>
<on-error>
</on-error>
</po
licies>