Polish contribution

See gh-21130

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/ValueObjectBinder.java

@@ -117,7 +117,10 @@ class ValueObjectBinder implements DataObjectBinder {
 	}
 
 	private boolean isEmptyDefaultValueAllowed(Class<?> type) {
-		return !type.isPrimitive() && !type.isEnum() && !isAggregate(type) && !type.getName().startsWith("java.lang");
+		if (type.isPrimitive() || type.isEnum() || isAggregate(type) || type.getName().startsWith("java.lang")) {
+			return false;
+		}
+		return true;
 	}
 
 	private boolean isAggregate(Class<?> type) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/DeferredLog.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/tomcat/TomcatGracefulShutdown.java

@@ -18,7 +18,7 @@ package org.springframework.boot.web.embedded.tomcat;
 
 import java.time.Duration;
 import java.util.ArrayList;
-import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.apache.catalina.Container;
@@ -107,7 +107,7 @@ class TomcatGracefulShutdown implements GracefulShutdown {
 	private List<Connector> getConnectors() {
 		List<Connector> connectors = new ArrayList<>();
 		for (Service service : this.tomcat.getServer().findServices()) {
-			connectors.addAll(Arrays.asList(service.findConnectors()));
+			Collections.addAll(connectors, service.findConnectors());
 		}
 		return connectors;
 	}