Remove QueryCollectorContext abstraction

server/src/main/java/org/elasticsearch/search/profile/query/CollectorResult.java

@@ -67,7 +67,7 @@ public class CollectorResult implements ToXContentObject, Writeable {
     /**
      * A list of children collectors "embedded" inside this collector
      */
-    private List<CollectorResult> children;
+    private final List<CollectorResult> children;
 
     public CollectorResult(String collectorName, String reason, long time, List<CollectorResult> children) {
         this.collectorName = collectorName;

server/src/main/java/org/elasticsearch/search/profile/query/InternalProfileCollector.java

@@ -47,15 +47,15 @@ public class InternalProfileCollector implements Collector {
      */
     private final InternalProfileCollector[] children;
 
-    public InternalProfileCollector(Collector collector, String reason, InternalProfileCollector... children) {
+    public InternalProfileCollector(Collector collector, String reason, Collector... children) {
         this.collector = new ProfileCollector(collector);
         this.reason = reason;
         this.collectorName = deriveCollectorName(collector);
         Objects.requireNonNull(children, "children collectors cannot be null");
-        for (InternalProfileCollector child : children) {
-            Objects.requireNonNull(child, "child collector cannot be null");
+        this.children = new InternalProfileCollector[children.length];
+        for (int i = 0; i < children.length; i++) {
+            this.children[i] = (InternalProfileCollector) Objects.requireNonNull(children[i], "child collector cannot be null");
         }
-        this.children = children;
     }
 
     /**