Cluster stats should not render empty http/transport types (#23735)

This commit changes the ClusterStatsNodes.NetworkTypes so that is does
not print out empty field names when no Transport or HTTP type is defined:

```
{
"network_types": {
        ...
        "http_types": {
          "": 2
        }
      }
}
```

is now rendered as:

```
{
"network_types": {
        ...
        "http_types": {
        }
      }
}
```

core/src/main/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsNodes.java

@@ -25,6 +25,7 @@
 import org.elasticsearch.action.admin.cluster.node.info.NodeInfo;
 import org.elasticsearch.action.admin.cluster.node.stats.NodeStats;
 import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.network.NetworkModule;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.transport.InetSocketTransportAddress;
@@ -544,7 +545,7 @@ static class NetworkTypes implements ToXContent {
         private final Map<String, AtomicInteger> transportTypes;
         private final Map<String, AtomicInteger> httpTypes;
 
-        private NetworkTypes(final List<NodeInfo> nodeInfos) {
+        NetworkTypes(final List<NodeInfo> nodeInfos) {
             final Map<String, AtomicInteger> transportTypes = new HashMap<>();
             final Map<String, AtomicInteger> httpTypes = new HashMap<>();
             for (final NodeInfo nodeInfo : nodeInfos) {
@@ -553,8 +554,12 @@ private NetworkTypes(final List<NodeInfo> nodeInfos) {
                     settings.get(NetworkModule.TRANSPORT_TYPE_KEY, NetworkModule.TRANSPORT_DEFAULT_TYPE_SETTING.get(settings));
                 final String httpType =
                     settings.get(NetworkModule.HTTP_TYPE_KEY, NetworkModule.HTTP_DEFAULT_TYPE_SETTING.get(settings));
-                transportTypes.computeIfAbsent(transportType, k -> new AtomicInteger()).incrementAndGet();
-                httpTypes.computeIfAbsent(httpType, k -> new AtomicInteger()).incrementAndGet();
+                if (Strings.hasText(transportType)) {
+                    transportTypes.computeIfAbsent(transportType, k -> new AtomicInteger()).incrementAndGet();
+                }
+                if (Strings.hasText(httpType)) {
+                    httpTypes.computeIfAbsent(httpType, k -> new AtomicInteger()).incrementAndGet();
+                }
             }
             this.transportTypes = Collections.unmodifiableMap(transportTypes);
             this.httpTypes = Collections.unmodifiableMap(httpTypes);

core/src/test/java/org/elasticsearch/action/admin/cluster/stats/ClusterStatsNodesTests.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.action.admin.cluster.stats;
+
+import org.elasticsearch.action.admin.cluster.node.info.NodeInfo;
+import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.common.network.NetworkModule;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.transport.LocalTransportAddress;
+import org.elasticsearch.common.xcontent.XContentType;
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
+import static org.elasticsearch.common.xcontent.XContentHelper.toXContent;
+
+public class ClusterStatsNodesTests extends ESTestCase {
+
+    /**
+     * Test that empty transport/http types are not printed out as part
+     * of the cluster stats xcontent output.
+     */
+    public void testNetworkTypesToXContent() throws Exception {
+        ClusterStatsNodes.NetworkTypes stats = new ClusterStatsNodes.NetworkTypes(emptyList());
+        assertEquals("{\"transport_types\":{},\"http_types\":{}}",
+                toXContent(stats, XContentType.JSON, true).utf8ToString());
+
+        List<NodeInfo> nodeInfos = singletonList(createNodeInfo("node_0", null, null));
+        stats = new ClusterStatsNodes.NetworkTypes(nodeInfos);
+        assertEquals("{\"transport_types\":{},\"http_types\":{}}",
+                toXContent(stats, XContentType.JSON, true).utf8ToString());
+
+        nodeInfos = Arrays.asList(createNodeInfo("node_1", "", ""),
+                                  createNodeInfo("node_2", "custom", "custom"),
+                                  createNodeInfo("node_3", null, "custom"));
+        stats = new ClusterStatsNodes.NetworkTypes(nodeInfos);
+        assertEquals("{"
+                + "\"transport_types\":{\"custom\":1},"
+                + "\"http_types\":{\"custom\":2}"
+        + "}", toXContent(stats, XContentType.JSON, true).utf8ToString());
+    }
+
+    private static NodeInfo createNodeInfo(String nodeId, String transportType, String httpType) {
+        Settings.Builder settings = Settings.builder();
+        if (transportType != null) {
+            settings.put(randomFrom(NetworkModule.TRANSPORT_TYPE_KEY,
+                    NetworkModule.TRANSPORT_TYPE_DEFAULT_KEY), transportType);
+        }
+        if (httpType != null) {
+            settings.put(randomFrom(NetworkModule.HTTP_TYPE_KEY,
+                    NetworkModule.HTTP_TYPE_DEFAULT_KEY), httpType);
+        }
+        return new NodeInfo(null, null,
+                new DiscoveryNode(nodeId, LocalTransportAddress.buildUnique(), null),
+                settings.build(), null, null, null, null, null, null, null, null, null);
+    }
+}