Check that the queueSize is a positive integer

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/listener/KafkaMessageListenerContainer.java

@@ -245,11 +245,11 @@ public class KafkaMessageListenerContainer implements SmartLifecycle {
 	/**
 	 * The maximum number of messages that are buffered by each concurrent {@link MessageListener} runner.
 	 * Increasing the value may increase throughput, but also increases the memory consumption.
-	 * Must be a power of 2.
+	 * Must be a positive number and a power of 2.
 	 * @param queueSize the queue size
 	 */
 	public void setQueueSize(int queueSize) {
-		Assert.isTrue(Integer.bitCount(queueSize) == 1, "'queueSize' must be a power of 2");
+		Assert.isTrue(queueSize > 0 && Integer.bitCount(queueSize) == 1, "'queueSize' must be a positive number and a power of 2");
 		this.queueSize = queueSize;
 	}
 

spring-integration-kafka/src/test/java/org/springframework/integration/kafka/listener/KafkaMessageDrivenChannelAdapterTests.java

@@ -89,6 +89,15 @@ public class KafkaMessageDrivenChannelAdapterTests extends AbstractMessageListen
 		catch (IllegalArgumentException e) {
 			assertThat(e.getMessage(), containsString("power of 2"));
 		}
+
+		try {
+			kafkaMessageListenerContainer.setQueueSize(Integer.MIN_VALUE);
+			fail("expected exception");
+		}
+		catch (IllegalArgumentException e) {
+			assertThat(e.getMessage(), containsString("positive number"));
+		}
+
 		kafkaMessageListenerContainer.setQueueSize(1024);
 
 		int expectedMessageCount = 100;