Polish Kafka properties

Closes gh-7672

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -4646,9 +4646,12 @@ Only a subset of the properties supported by Kafka are available via the `KafkaP
 class. If you wish to configure the producer or consumer with additional properties that
 are not directly supported, use the following:
 
-`spring.kafka.properties.foo.bar=baz`
+[source,properties,indent=0]
+----
+	spring.kafka.properties.foo.bar=baz
+----
 
-This sets the common `foo.bar` kafka property to `baz`.
+This sets the common `foo.bar` Kafka property to `baz`.
 
 These properties will be shared by both the consumer and producer factory beans.
 If you wish to customize these components with different properties, such as to use a
@@ -4659,6 +4662,8 @@ different metrics reader for each, you can override the bean definitions, as fol
 include::{code-examples}/kafka/KafkaSpecialProducerConsumerConfigExample.java[tag=configuration]
 ----
 
+
+
 [[boot-features-restclient]]
 == Calling REST services
 If you need to call remote REST services from your application, you can use Spring

spring-boot-docs/src/main/java/org/springframework/boot/kafka/KafkaSpecialProducerConsumerConfigExample.java

@@ -32,12 +32,11 @@ import org.springframework.kafka.core.DefaultKafkaProducerFactory;
 import org.springframework.kafka.core.ProducerFactory;
 
 /**
- * Example custom kafka configuration beans used when the user wants to
- * apply different common properties to the producer and consumer.
+ * Example custom kafka configuration beans used when the user wants to apply different
+ * common properties to the producer and consumer.
  *
  * @author Gary Russell
  * @since 1.5
- *
  */
 public class KafkaSpecialProducerConsumerConfigExample {
 
@@ -65,7 +64,8 @@ public class KafkaSpecialProducerConsumerConfigExample {
 		 */
 		@Bean
 		public ConsumerFactory<?, ?> kafkaConsumerFactory(KafkaProperties properties) {
-			Map<String, Object> consumererProperties = properties.buildConsumerProperties();
+			Map<String, Object> consumererProperties = properties
+					.buildConsumerProperties();
 			consumererProperties.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG,
 					MyConsumerMetricsReporter.class);
 			return new DefaultKafkaConsumerFactory<Object, Object>(consumererProperties);