Fix new Sonar issues

Author: garyrussell

spring-kafka/src/main/java/org/springframework/kafka/core/DefaultKafkaProducerFactory.java

@@ -536,11 +536,11 @@ public void close() {
 		@SuppressWarnings("deprecation")
 		@Deprecated
 		public void close(long timeout, @Nullable TimeUnit unit) {
-			close(Duration.ofMillis(unit.toMillis(timeout)));
+			close(unit == null ? null : Duration.ofMillis(unit.toMillis(timeout)));
 		}
 
 		@Override
-		public void close(Duration timeout) {
+		public void close(@Nullable Duration timeout) {
 			if (this.cache != null) {
 				if (this.txFailed) {
 					if (logger.isWarnEnabled()) {

spring-kafka/src/main/java/org/springframework/kafka/core/KafkaAdmin.java

@@ -65,7 +65,7 @@ public class KafkaAdmin implements ApplicationContextAware, SmartInitializingSin
 
 	private static final int DEFAULT_OPERATION_TIMEOUT = 30;
 
-	private final static Log LOGGER = LogFactory.getLog(KafkaAdmin.class);
+	private static final Log LOGGER = LogFactory.getLog(KafkaAdmin.class);
 
 	private final Map<String, Object> config;