Address PR feedback

Author: mark-vieira

buildSrc/src/main/java/org/elasticsearch/gradle/LazyPropertyList.java

@@ -40,7 +40,7 @@ public boolean contains(Object o) {
 
     @Override
     public Iterator<T> iterator() {
-        return delegate.stream().peek(this::validate).map(PropertyListEntry::getValue).collect(Collectors.toList()).iterator();
+        return delegate.stream().peek(this::validate).map(PropertyListEntry::getValue).iterator();
     }
 
     @Override

buildSrc/src/main/java/org/elasticsearch/gradle/test/RestTestRunnerTask.java

@@ -3,7 +3,6 @@
 import org.elasticsearch.gradle.testclusters.ElasticsearchCluster;
 import org.gradle.api.tasks.CacheableTask;
 import org.gradle.api.tasks.Nested;
-import org.gradle.api.tasks.Optional;
 import org.gradle.api.tasks.testing.Test;
 
 import java.util.ArrayList;
@@ -28,7 +27,6 @@ public RestTestRunnerTask() {
     }
 
     @Nested
-    @Optional
     public Collection<ElasticsearchCluster> getClusters() {
         return clusters;
     }