Find unique field values in ElasticSearch using Spring Data ElasticsearchRepository

I have an interface extending ElasticsearchRepository and have successfully created methods to search such as:

Page<AuditResult> findByCustomerCodeAndHost(String customerCode, String host, Pageable pageable);

Now, I want an endpoint to hit that would return me all of the possible host values for that customerCode so that I can build a dropdown list in my front end to select a value to send to that findByCustomerCodeAndHost endpoint, something like:

List<String> findUniqueHostByCustomerCode(String customerCode)

Is this even possible using an ElasticsearchRepository?

I know there is the Distinct keyword I can use like List<String> findDistinctByCustomerCode(String customerCode); but this doesn't let me specify the host field.

Edit: Here is how I accomplished what I wanted but as it is not currently possible to actually do this with ElasticsearchRepository it isn't an actual "answer".

I created a Spring web @RestController class that I exposed a @GetMapping REST endpoint that executed an aggregation query.

The query in kibana console:

GET auditresult/_search
{
  "size": "0",
  "aggs" : {
    "uniq_custCode" : {
      "terms" : { "field" : "customerCode", "include": "<CUSTOMER_CODE>" },
        "aggs" : {
          "uniq_host" : {
           "terms" : { "field" : "host"}
          }
        }
      }
    }
  }

And, based off this question ElasticSearch aggregation with Java I came up with

@GetMapping("/hosts/{customerCode}")
String getHostsByCustomer(@PathVariable String customerCode) {
    SearchRequest searchRequest = new SearchRequest("auditresult");
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder().size(0);
    IncludeExclude ie = new IncludeExclude(customerCode, "");
    TermsAggregationBuilder aggregation =
            AggregationBuilders
                    .terms("uniq_custCode").includeExclude(ie)
                    .field("customerCode")
                    .subAggregation(
                            AggregationBuilders
                                    .terms("uniq_host")
                                    .field("host")
                    );
    searchSourceBuilder.aggregation(aggregation);
    searchRequest.source(searchSourceBuilder);
    try {
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
        Terms cust = searchResponse.getAggregations().get("uniq_custCode");
        StringBuilder sb = new StringBuilder();
        sb.append("{\"hosts\":[");
        for (Terms.Bucket bucket : cust.getBuckets()) {
            Terms hosts = bucket.getAggregations().get("uniq_hosts");
            for (Terms.Bucket host : hosts.getBuckets()) {
                System.out.println(host.getKey());
                sb.append("\"" + host.getKey() + "\",");
            }
        }
        String out = sb.toString();
        out = out.substring(0, out.length() - 1);
        return out + "]}";
    } catch (IOException e) {
        e.printStackTrace();
        return "{\"hosts\":[]}";
    }
}