Refer https://aem6solutions.blogspot.com/2019/11/cache-clearance-in-dispatcher.html 

check now 

Check the updated link .

Check your settings.xml in .m2 folder .

Check User Management API methodsRef: https://developer.adobe.com/experience-manager/reference-materials/6-5/javadoc/org/apache/jackrabbit/api/security/user/UserManager.html 

For supported MIME types refer https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/assets/file-format-support.html?lang=en If it is not listed here , will recommend to raise a support ticket to adobe. Thanks

A web tier config pipeline Deploys HTTPD/Dispatcher configurations Refer experienceleague.adobe.com/docs/experience-manager-cloud-service/content/implementing/using-cloud-manager/cicd-pipelines/configuring-production-pipelines.html?lang=en#web-tier-config  Thanks

Using clientlib at component level depends upon the requirement .There is no as such fixed rule for this. For more details on clientlibs refer : experienceleague.adobe.com/docs/experience-manager-65/developing/introduction/clientlibs.html?lang=en 

Any changes in dispatcher module can only be deployed via pipeline in AEM as a cloud service .

in addition to @arunpatidar  @DEBAL_DAS   refer https://experienceleague.adobe.com/docs/experience-manager-65/developing/platform/query-builder/querybuilder-predicate-reference.html?lang=enfor query builder predicate reference.