Use addAll instead of manual array to collection copy

Closes gh-7539

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/server/RestartServer.java

@@ -20,6 +20,7 @@ import java.io.File;
 import java.io.IOException;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Map.Entry;
 import java.util.Set;
@@ -141,9 +142,7 @@ public class RestartServer {
 		ClassLoader classLoader = this.classLoader;
 		while (classLoader != null) {
 			if (classLoader instanceof URLClassLoader) {
-				for (URL url : ((URLClassLoader) classLoader).getURLs()) {
+				Collections.addAll(urls, ((URLClassLoader) classLoader).getURLs());
-					urls.add(url);
-				}
 			}
 			classLoader = classLoader.getParent();
 		}

spring-boot/src/main/java/org/springframework/boot/context/ConfigurationWarningsApplicationContextInitializer.java

@@ -183,9 +183,7 @@ public class ConfigurationWarningsApplicationContextInitializer
 
 		private void addPackages(Set<String> packages, String[] values) {
 			if (values != null) {
-				for (String value : values) {
+				Collections.addAll(packages, values);
-					packages.add(value);
-				}
 			}
 		}