From 3822541d8952da50ca71c37eb0e64383aa259f97 Mon Sep 17 00:00:00 2001
From: Christine Poerschke <cpoerschke@apache.org>
Date: Fri, 25 Jun 2021 17:24:24 +0100
Subject: [PATCH] SOLR-15485: discourage Collections.singleton.forEach use
 (#179)

Resolved Conflicts:
	gradle/validation/validate-source-patterns.gradle
	solr/core/src/java/org/apache/solr/core/CoreContainer.java
---
 .../java/org/apache/solr/core/CoreContainer.java |  4 +---
 .../solr/BaseDistributedSearchTestCase.java      |  4 +---
 .../cloud/AbstractFullDistribZkTestBase.java     | 16 ++++------------
 3 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/solr/core/src/java/org/apache/solr/core/CoreContainer.java b/solr/core/src/java/org/apache/solr/core/CoreContainer.java
index 2388d38e2086..2c4ab4cad088 100644
--- a/solr/core/src/java/org/apache/solr/core/CoreContainer.java
+++ b/solr/core/src/java/org/apache/solr/core/CoreContainer.java
@@ -1138,9 +1138,7 @@ public void shutdown() {
       } finally {
         try {
           if (updateShardHandler != null) {
-            customThreadPool.submit(() -> Collections.singleton(shardHandlerFactory).parallelStream().forEach(c -> {
-              updateShardHandler.close();
-            }));
+            customThreadPool.submit(() -> updateShardHandler.close());
           }
         } finally {
           try {
diff --git a/solr/test-framework/src/java/org/apache/solr/BaseDistributedSearchTestCase.java b/solr/test-framework/src/java/org/apache/solr/BaseDistributedSearchTestCase.java
index 66c1974a7262..26f90b2d7ea8 100644
--- a/solr/test-framework/src/java/org/apache/solr/BaseDistributedSearchTestCase.java
+++ b/solr/test-framework/src/java/org/apache/solr/BaseDistributedSearchTestCase.java
@@ -414,9 +414,7 @@ protected String getShardsString() {
   protected void destroyServers() throws Exception {
     ExecutorService customThreadPool = ExecutorUtil.newMDCAwareCachedThreadPool(new SolrNamedThreadFactory("closeThreadPool"));
     
-    customThreadPool.submit(() -> Collections.singleton(controlClient).parallelStream().forEach(c -> {
-      IOUtils.closeQuietly(c);
-    }));
+    customThreadPool.submit(() -> IOUtils.closeQuietly(controlClient));
 
     customThreadPool.submit(() -> {
       try {
diff --git a/solr/test-framework/src/java/org/apache/solr/cloud/AbstractFullDistribZkTestBase.java b/solr/test-framework/src/java/org/apache/solr/cloud/AbstractFullDistribZkTestBase.java
index 1fb1efb49d24..3976adb05dac 100644
--- a/solr/test-framework/src/java/org/apache/solr/cloud/AbstractFullDistribZkTestBase.java
+++ b/solr/test-framework/src/java/org/apache/solr/cloud/AbstractFullDistribZkTestBase.java
@@ -1732,25 +1732,17 @@ public void distribTearDown() throws Exception {
   protected void destroyServers() throws Exception {
     ExecutorService customThreadPool = ExecutorUtil.newMDCAwareCachedThreadPool(new SolrNamedThreadFactory("closeThreadPool"));
     
-    customThreadPool.submit(() -> Collections.singleton(commonCloudSolrClient).parallelStream().forEach(c -> {
-      IOUtils.closeQuietly(c);
-    }));
+    customThreadPool.submit(() -> IOUtils.closeQuietly(commonCloudSolrClient));
     
-    customThreadPool.submit(() -> Collections.singleton(controlClient).parallelStream().forEach(c -> {
-      IOUtils.closeQuietly(c);
-    }));
+    customThreadPool.submit(() -> IOUtils.closeQuietly(controlClient));
     
     customThreadPool.submit(() -> coreClients.parallelStream().forEach(c -> {
       IOUtils.closeQuietly(c);
     }));
 
-    customThreadPool.submit(() -> Collections.singletonList(controlClientCloud).parallelStream().forEach(c -> {
-      IOUtils.closeQuietly(c);
-    }));
+    customThreadPool.submit(() -> IOUtils.closeQuietly(controlClientCloud));
 
-    customThreadPool.submit(() -> Collections.singletonList(cloudClient).parallelStream().forEach(c -> {
-      IOUtils.closeQuietly(c);
-    }));
+    customThreadPool.submit(() -> IOUtils.closeQuietly(cloudClient));
 
     ExecutorUtil.shutdownAndAwaitTermination(customThreadPool);