Apply Stream API best practices

Author: ppkarwasz

log4j-api/src/main/java/org/apache/logging/log4j/spi/LoggerRegistry.java

@@ -18,7 +18,6 @@
 
 import static java.util.Objects.requireNonNull;
 
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -28,6 +27,7 @@
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.stream.Collectors;
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.MessageFactory;
 import org.apache.logging.log4j.message.ParameterizedMessageFactory;
@@ -158,19 +158,19 @@ public LoggerRegistry(final MapFactory<T> mapFactory) {
     }
 
     public Collection<T> getLoggers() {
-        return getLoggers(new ArrayList<>());
-    }
-
-    public Collection<T> getLoggers(final Collection<T> destination) {
-        requireNonNull(destination, "destination");
         readLock.lock();
         try {
-            loggerByMessageFactoryByName.values().stream()
+            return loggerByMessageFactoryByName.values().stream()
                     .flatMap(loggerByMessageFactory -> loggerByMessageFactory.values().stream())
-                    .forEach(destination::add);
+                    .collect(Collectors.toList());
         } finally {
             readLock.unlock();
         }
+    }
+
+    public Collection<T> getLoggers(final Collection<T> destination) {
+        requireNonNull(destination, "destination");
+        destination.addAll(getLoggers());
         return destination;
     }