MINOR: fix checkstyle issue in ConsumerConfig.java (#8038)

Reviewers: Ismael Juma <ismael@juma.me.uk>

clients/src/main/java/org/apache/kafka/clients/consumer/ConsumerConfig.java

@@ -103,17 +103,17 @@ public class ConsumerConfig extends AbstractConfig {
      * <code>partition.assignment.strategy</code>
      */
     public static final String PARTITION_ASSIGNMENT_STRATEGY_CONFIG = "partition.assignment.strategy";
-    private static final String PARTITION_ASSIGNMENT_STRATEGY_DOC = "A list of class names or class types, "+
-            "ordered by preference, of supported partition assignment "+
-            "strategies that the client will use to distribute partition "+
-            "ownership amongst consumer instances when group management is "+
-            "used.<p>In addition to the default class specified below, "+
-            "you can use the " + 
-            "<code>org.apache.kafka.clients.consumer.RoundRobinAssignor</code>"+
-            "class for round robin assignments of partitions to consumers. "+
+    private static final String PARTITION_ASSIGNMENT_STRATEGY_DOC = "A list of class names or class types, " +
+            "ordered by preference, of supported partition assignment " +
+            "strategies that the client will use to distribute partition " +
+            "ownership amongst consumer instances when group management is " +
+            "used.<p>In addition to the default class specified below, " +
+            "you can use the " +
+            "<code>org.apache.kafka.clients.consumer.RoundRobinAssignor</code>" +
+            "class for round robin assignments of partitions to consumers. " +
             "</p><p>Implementing the " +
-            "<code>org.apache.kafka.clients.consumer.ConsumerPartitionAssignor"+
-            "</code> interface allows you to plug in a custom assignment"+
+            "<code>org.apache.kafka.clients.consumer.ConsumerPartitionAssignor" +
+            "</code> interface allows you to plug in a custom assignment" +
             "strategy.";
 
     /**