fix wrong test example

Signed-off-by: moonyoungCHAE <[email protected]>

Author: moonyoungCHAE

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

@@ -149,7 +149,7 @@ The following example configuration creates topics called `cat` and `hat` with f
 public class MyTests {
 
     @ClassRule
-    private static EmbeddedKafkaRule embeddedKafka = new EmbeddedKafkaRule(1, false, 5, "cat", "hat");
+    public static EmbeddedKafkaRule embeddedKafka = new EmbeddedKafkaRule(1, false, 5, "cat", "hat");
 
     @Test
     public void test() {

spring-kafka/src/main/java/org/springframework/kafka/support/converter/BatchMessagingMessageConverter.java

@@ -169,17 +169,18 @@ public Message<?> toMessage(List<ConsumerRecord<?, ?>> records, @Nullable Acknow
 				new KafkaMessageHeaders(this.generateMessageId, this.generateTimestamp);
 
 		Map<String, Object> rawHeaders = kafkaMessageHeaders.getRawHeaders();
-		List<Object> payloads = new ArrayList<>();
-		List<Object> keys = new ArrayList<>();
-		List<String> topics = new ArrayList<>();
-		List<Integer> partitions = new ArrayList<>();
-		List<Long> offsets = new ArrayList<>();
-		List<String> timestampTypes = new ArrayList<>();
-		List<Long> timestamps = new ArrayList<>();
-		List<Map<String, Object>> convertedHeaders = new ArrayList<>();
-		List<Headers> natives = new ArrayList<>();
-		List<ConsumerRecord<?, ?>> raws = new ArrayList<>();
-		List<ConversionException> conversionFailures = new ArrayList<>();
+		int batchSize = records.size();
+		List<Object> payloads = new ArrayList<>(batchSize);
+		List<Object> keys = new ArrayList<>(batchSize);
+		List<String> topics = new ArrayList<>(batchSize);
+		List<Integer> partitions = new ArrayList<>(batchSize);
+		List<Long> offsets = new ArrayList<>(batchSize);
+		List<String> timestampTypes = new ArrayList<>(batchSize);
+		List<Long> timestamps = new ArrayList<>(batchSize);
+		List<Map<String, Object>> convertedHeaders = new ArrayList<>(batchSize);
+		List<Headers> natives = new ArrayList<>(batchSize);
+		List<ConsumerRecord<?, ?>> raws = new ArrayList<>(batchSize);
+		List<ConversionException> conversionFailures = new ArrayList<>(batchSize);
 
 		addToRawHeaders(rawHeaders, convertedHeaders, natives, raws, conversionFailures);
 		commonHeaders(acknowledgment, consumer, rawHeaders, keys, topics, partitions, offsets, timestampTypes,