Adapt to new upstream code changes

There are two main changes impacting the code when upgrading top 7.3.0.

The first is introduction of pluggable Node roles:
- elastic/elasticsearch#43175

The second is renaming the Action class to ActionType:
- elastic/elasticsearch#43778

src/main/java/org/compuscene/metrics/prometheus/PrometheusMetricsCollector.java

@@ -24,7 +24,7 @@
 import org.elasticsearch.action.admin.indices.stats.IndexStats;
 import org.elasticsearch.action.admin.indices.stats.IndicesStatsResponse;
 import org.elasticsearch.cluster.health.ClusterIndexHealth;
-import org.elasticsearch.cluster.node.DiscoveryNode.Role;
+import org.elasticsearch.cluster.node.DiscoveryNodeRole;
 import org.elasticsearch.http.HttpStats;
 import org.elasticsearch.indices.NodeIndicesStats;
 import org.elasticsearch.indices.breaker.AllCircuitBreakerStats;
@@ -129,14 +129,17 @@ private void registerNodeMetrics() {
 
     private void updateNodeMetrics(NodeStats ns) {
         if (ns != null) {
+
+            // Plugins can introduce custom node roles from 7.3.0: https://github.com/elastic/elasticsearch/pull/43175
+            // TODO(lukas-vlcek): List of node roles can not be static but needs to be created dynamically.
             Map<String, Integer> roles = new HashMap<>();
 
             roles.put("master", 0);
             roles.put("data", 0);
             roles.put("ingest", 0);
 
-            for (Role r : ns.getNode().getRoles()) {
-                roles.put(r.getRoleName(), 1);
+            for (DiscoveryNodeRole r : ns.getNode().getRoles()) {
+                roles.put(r.roleName(), 1);
             }
 
             for (String k : roles.keySet()) {

src/main/java/org/elasticsearch/action/NodePrometheusMetricsAction.java

@@ -21,18 +21,16 @@
 /**
  * Action class for Prometheus Exporter plugin.
  */
-public class NodePrometheusMetricsAction extends Action<NodePrometheusMetricsResponse> {
+public class NodePrometheusMetricsAction extends ActionType<NodePrometheusMetricsResponse> {
+    // TODO(lukas-vlcek): There are ongoing changes for ActionType class. This code needs additional review.
+    // - https://github.com/elastic/elasticsearch/pull/43778
+    // - https://github.com/elastic/elasticsearch/commit/b33ffc1ae06035e934277f17c4b5d9851f607056#diff-80df90ca727aadbbe854902f81bda313
+    // - https://github.com/elastic/elasticsearch/commit/5a9f81791a1be7fe6dd97728384ebafb189ab211#diff-80df90ca727aadbbe854902f81bda313
     public static final NodePrometheusMetricsAction INSTANCE = new NodePrometheusMetricsAction();
     public static final String NAME = "cluster:monitor/prometheus/metrics";
 
     private NodePrometheusMetricsAction() {
-        super(NAME);
-    }
-
-    @Override
-    @SuppressWarnings("deprecation")
-    public NodePrometheusMetricsResponse newResponse() {
-        throw new UnsupportedOperationException("usage of Streamable is to be replaced by Writeable");
+        super(NAME, null);
     }
 
     @Override