Add basic test for header.

src/test/kotlin/Tests.kt

@@ -26,6 +26,7 @@ import java.util.stream.Stream
 import org.apache.kafka.clients.consumer.ConsumerConfig
 import org.apache.kafka.clients.consumer.ConsumerRecord
 import org.apache.kafka.clients.consumer.KafkaConsumer
+import org.apache.kafka.common.header.internals.RecordHeader
 import org.apache.kafka.common.serialization.StringDeserializer
 import org.apache.logging.log4j.LogManager
 import org.assertj.core.api.Assertions.assertThat
@@ -100,6 +101,7 @@ class Tests {
         val record = totalConsumerRecords.find { value -> value.topic() == topic }!!
         val recordKey = record.key()
         val recordMessage = record.value()
+        val headers = record.headers()
 
         val report = totalConsumerRecords.find { value -> value.topic() == reportingTopic }!!
         val reportKey = report.key()
@@ -121,6 +123,10 @@ class Tests {
             {
                 assertThat(reportMessage)
                     .isEqualTo(params.expectedReportValue)
+            },
+            {
+                assertThat(headers)
+                    .contains(RecordHeader("sessionId", "session1".toByteArray()))
             }
         )
     }