Remove x-pack aggregations. (#59)

This PR removes the x-pack aggregations: string_stats, top_metrics and inference.

Resolves #51
Relates #2

client/rest-high-level/src/main/java/org/elasticsearch/client/RestHighLevelClient.java

@@ -54,12 +54,6 @@
 import org.elasticsearch.action.support.master.AcknowledgedResponse;
 import org.elasticsearch.action.update.UpdateRequest;
 import org.elasticsearch.action.update.UpdateResponse;
-import org.elasticsearch.client.analytics.InferencePipelineAggregationBuilder;
-import org.elasticsearch.client.analytics.ParsedInference;
-import org.elasticsearch.client.analytics.ParsedStringStats;
-import org.elasticsearch.client.analytics.ParsedTopMetrics;
-import org.elasticsearch.client.analytics.StringStatsAggregationBuilder;
-import org.elasticsearch.client.analytics.TopMetricsAggregationBuilder;
 import org.elasticsearch.client.core.CountRequest;
 import org.elasticsearch.client.core.CountResponse;
 import org.elasticsearch.client.core.GetSourceRequest;
@@ -1802,9 +1796,6 @@ static List<NamedXContentRegistry.Entry> getDefaultNamedXContents() {
         map.put(IpRangeAggregationBuilder.NAME, (p, c) -> ParsedBinaryRange.fromXContent(p, (String) c));
         map.put(TopHitsAggregationBuilder.NAME, (p, c) -> ParsedTopHits.fromXContent(p, (String) c));
         map.put(CompositeAggregationBuilder.NAME, (p, c) -> ParsedComposite.fromXContent(p, (String) c));
-        map.put(StringStatsAggregationBuilder.NAME, (p, c) -> ParsedStringStats.PARSER.parse(p, (String) c));
-        map.put(TopMetricsAggregationBuilder.NAME, (p, c) -> ParsedTopMetrics.PARSER.parse(p, (String) c));
-        map.put(InferencePipelineAggregationBuilder.NAME, (p, c) -> ParsedInference.fromXContent(p, (String ) (c)));
         List<NamedXContentRegistry.Entry> entries = map.entrySet().stream()
                 .map(entry -> new NamedXContentRegistry.Entry(Aggregation.class, new ParseField(entry.getKey()), entry.getValue()))
                 .collect(Collectors.toList());