Resolve more Gradle task validation warnings (#47825)

(cherry picked from commit 82e3d5ea31101f4c27e69162684c3aa4fb2193a4)

# Conflicts:
#	buildSrc/src/main/groovy/org/elasticsearch/gradle/doc/RestTestsFromSnippetsTask.groovy

buildSrc/src/main/groovy/org/elasticsearch/gradle/doc/RestTestsFromSnippetsTask.groovy

@@ -23,6 +23,7 @@ import groovy.transform.PackageScope
 import org.elasticsearch.gradle.doc.SnippetsTask.Snippet
 import org.gradle.api.InvalidUserDataException
 import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.OutputDirectory
 
 import java.nio.file.Files
@@ -58,6 +59,9 @@ class RestTestsFromSnippetsTask extends SnippetsTask {
     @OutputDirectory
     File testRoot = project.file('build/rest')
 
+    @Internal
+    Set<String> names = new HashSet<>()
+
     RestTestsFromSnippetsTask() {
         project.afterEvaluate {
             // Wait to set this so testRoot can be customized

buildSrc/src/main/java/org/elasticsearch/gradle/testclusters/ElasticsearchCluster.java

@@ -104,6 +104,7 @@ public class ElasticsearchCluster implements TestClusterConfiguration, Named {
         }
     }
 
+    @Internal
     ElasticsearchNode getFirstNode() {
         return nodes.getAt(clusterName + "-0");
     }

buildSrc/src/main/java/org/elasticsearch/gradle/testclusters/ElasticsearchNode.java

@@ -183,6 +183,7 @@ public class ElasticsearchNode implements TestClusterConfiguration {
         return distributions.get(currentDistro).getVersion();
     }
 
+    @Internal
     public Path getDistroDir() {
         return workingDir.resolve("distro").resolve(getVersion() + "-" + testDistribution);
     }