In order for the code bellow to work:

► Make sure to update the variables ("solrUrl", "collectionName", ...) with your information.

final String[] solrUrl = { "http://localhost:8983/solr" };

final CloudSolrClient cloudSolrClient = new CloudSolrClient.Builder(Arrays.asList(solrUrl)).build();

// list config sets
{
    final ConfigSetAdminRequest.List adminRequest = new ConfigSetAdminRequest.List();

    ConfigSetAdminResponse adminResponse = adminRequest.process(cloudSolrClient);

    System.out.println(adminResponse);
}

cloudSolrClient.close();

Create a new Config Set ("configSetName") based on an existing Config Set ("baseConfigSetName").

final String[] solrUrl = { "http://localhost:8983/solr" };

final CloudSolrClient cloudSolrClient = new CloudSolrClient.Builder(Arrays.asList(solrUrl)).build();

final String configSetName = "_default_clone";
final String baseConfigSetName = "_default";

// create config set
{
    final ConfigSetAdminRequest.Create adminRequest = new ConfigSetAdminRequest.Create();
    adminRequest.setConfigSetName(configSetName);
    adminRequest.setBaseConfigSetName(baseConfigSetName);

    ConfigSetAdminResponse adminResponse = adminRequest.process(cloudSolrClient);

    System.out.println(adminResponse);
}

cloudSolrClient.close();

final String[] solrUrl = { "http://localhost:8983/solr" };

final CloudSolrClient cloudSolrClient = new CloudSolrClient.Builder(Arrays.asList(solrUrl)).build();

final String configSetName = "_default_clone";

// delete config set
{
    final ConfigSetAdminRequest.Delete adminRequest = new ConfigSetAdminRequest.Delete();
    adminRequest.setConfigSetName(configSetName);

    ConfigSetAdminResponse adminResponse = adminRequest.process(cloudSolrClient);

    System.out.println(adminResponse);
}

cloudSolrClient.close();