title: How to create Solr core via admin API without creating instance directory with config files?
body: <p>I'm using Solr version 7.7.3. According to <a href="https://solr.apache.org/guide/7_7/coreadmin-api.html" rel="nofollow noreferrer">documentation</a> I can use pre-defined config sets or pass config file name in the CREATE call, but there is a problem. When I passing configSet parameter Solr share this config set between all cores which were created using this set, so all fields which would be added to any of them will be added to the schema of this single config set. That is not suitable for me.
  Otherwise let say I don't have access to the machine where Solr installed and I cannot create folder and put config manually. I want fully automate this process without any additional proxy applications.
  Note that I can do what I want from command line: <em>solr create -c test_core</em>. After that I can see own default configuration under the new core.</p>
  <p>I need to do the same via admin API call.</p>