From 4308e0c5b4e77e0f5fe0ae09ec8f6c6efc361a2a Mon Sep 17 00:00:00 2001
From: Alexander Fedulov <1492164+afedulov@users.noreply.github.com>
Date: Fri, 21 Feb 2020 15:46:48 +0100
Subject: [PATCH] [FLINK-16222][core] Relax Plugin bounded type parameter
 constraint

---
 .../java/org/apache/flink/core/plugin/PluginLoader.java    | 7 +++----
 .../java/org/apache/flink/core/plugin/PluginManager.java   | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/flink-core/src/main/java/org/apache/flink/core/plugin/PluginLoader.java b/flink-core/src/main/java/org/apache/flink/core/plugin/PluginLoader.java
index 6dbe6753ab266..7287399cf39e6 100644
--- a/flink-core/src/main/java/org/apache/flink/core/plugin/PluginLoader.java
+++ b/flink-core/src/main/java/org/apache/flink/core/plugin/PluginLoader.java
@@ -20,7 +20,6 @@
 
 import org.apache.flink.annotation.VisibleForTesting;
 import org.apache.flink.util.ArrayUtils;
-import org.apache.flink.util.ChildFirstClassLoader;
 import org.apache.flink.util.TemporaryClassLoaderContext;
 
 import javax.annotation.concurrent.ThreadSafe;
@@ -35,7 +34,7 @@
 
 /**
  * A {@link PluginLoader} is used by the {@link PluginManager} to load a single plugin. It is essentially a combination
- * of a {@link ChildFirstClassLoader} and {@link ServiceLoader}. This class can locate and load service implementations
+ * of a {@link PluginClassLoader} and {@link ServiceLoader}. This class can locate and load service implementations
  * from the plugin for a given SPI. The {@link PluginDescriptor}, which among other information contains the resource
  * URLs, is provided at construction.
  */
@@ -69,7 +68,7 @@ public static PluginLoader create(PluginDescriptor pluginDescriptor, ClassLoader
 	 * @param <P> Type of the requested plugin service.
 	 * @return An iterator of all implementations of the given service interface that could be loaded from the plugin.
 	 */
-	public <P extends Plugin> Iterator<P> load(Class<P> service) {
+	public <P> Iterator<P> load(Class<P> service) {
 		try (TemporaryClassLoaderContext ignored = TemporaryClassLoaderContext.of(pluginClassLoader)) {
 			return new ContextClassLoaderSettingIterator<>(
 				ServiceLoader.load(service, pluginClassLoader).iterator(),
@@ -83,7 +82,7 @@ public <P extends Plugin> Iterator<P> load(Class<P> service) {
 	 *
 	 * @param <P> type of the iterated plugin element.
 	 */
-	static class ContextClassLoaderSettingIterator<P extends Plugin> implements Iterator<P> {
+	static class ContextClassLoaderSettingIterator<P> implements Iterator<P> {
 
 		private final Iterator<P> delegate;
 		private final ClassLoader pluginClassLoader;
diff --git a/flink-core/src/main/java/org/apache/flink/core/plugin/PluginManager.java b/flink-core/src/main/java/org/apache/flink/core/plugin/PluginManager.java
index 23857326d5a6d..8d50585411a36 100644
--- a/flink-core/src/main/java/org/apache/flink/core/plugin/PluginManager.java
+++ b/flink-core/src/main/java/org/apache/flink/core/plugin/PluginManager.java
@@ -63,7 +63,7 @@ public PluginManager(Collection<PluginDescriptor> pluginDescriptors, ClassLoader
 	 * @param <P> Type of the requested plugin service.
 	 * @return Iterator over all implementations of the given service that could be loaded from all known plugins.
 	 */
-	public <P extends Plugin> Iterator<P> load(Class<P> service) {
+	public <P> Iterator<P> load(Class<P> service) {
 		ArrayList<Iterator<P>> combinedIterators = new ArrayList<>(pluginDescriptors.size());
 		for (PluginDescriptor pluginDescriptor : pluginDescriptors) {
 			PluginLoader pluginLoader = PluginLoader.create(pluginDescriptor, parentClassLoader, alwaysParentFirstPatterns);