title: How to generate cache key in Mule4 for accesstoken?
body: <p>I have configured my caching scope with default key generation process.In the caching scope it caches  <strong>accesstoken</strong>
  This caching logic i keep in seperate flow.</p>
  
  <p>eg:</p>
  
  <pre><code>&lt;os:object-store name="Object_store" doc:name="Object store" persistent="false" maxEntries="10" entryTtl="7" entryTtlUnit="HOURS" expirationIntervalUnit="HOURS"/&gt;
      &lt;ee:object-store-caching-strategy
          name="Caching_Strategy" doc:name="Caching Strategy" objectStore="Object_store" /&gt;
      &lt;flow name="sys-caching:\tokenFlow"&gt;
          &lt;ee:cache doc:name="Cache"  cachingStrategy-ref="Caching_Strategy"&gt;
              &lt;flow-ref doc:name="getchallenge"  name="sys-authentication:\get-challenge-subflow"/&gt;
              &lt;flow-ref doc:name="getaccesstoken"name="sys-authentication:\get-token-subflow"/&gt;
          &lt;/ee:cache&gt;
  &lt;/flow&gt;
  </code></pre>
  
  <p>I call above caching flow( to get accesstoken) in different scenarios, when making GET/POST calls with external endpoints.
  Here my issue is, each time the payload is different for the caching scope. So, it makes new calls to get new token and more tokens are getting cached. If payload is same, cache returns same token.</p>
  
  <p>My requiremnet is, <strong>do not depend on payload.</strong>. Just return the cached accesstoken for 8 hours(caching period)
  How can i configure cache key for this?</p>