Remove direct dependency on Kafka's IsolationLevel

Closes gh-20811

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/kafka/KafkaProperties.java

@@ -30,7 +30,6 @@ import org.apache.kafka.clients.CommonClientConfigs;
 import org.apache.kafka.clients.consumer.ConsumerConfig;
 import org.apache.kafka.clients.producer.ProducerConfig;
 import org.apache.kafka.common.config.SslConfigs;
-import org.apache.kafka.common.requests.IsolationLevel;
 import org.apache.kafka.common.serialization.StringDeserializer;
 import org.apache.kafka.common.serialization.StringSerializer;
 
@@ -1222,6 +1221,31 @@ public class KafkaProperties {
 
 	}
 
+	public enum IsolationLevel {
+
+		/**
+		 * Read everything including aborted transactions.
+		 */
+		READ_UNCOMMITTED((byte) 0),
+
+		/**
+		 * Read records from committed transactions, in addition to records not part of
+		 * transactions.
+		 */
+		READ_COMMITTED((byte) 1);
+
+		private final byte id;
+
+		IsolationLevel(byte id) {
+			this.id = id;
+		}
+
+		public byte id() {
+			return this.id;
+		}
+
+	}
+
 	@SuppressWarnings("serial")
 	private static class Properties extends HashMap<String, Object> {
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/kafka/KafkaPropertiesTests.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.kafka;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.kafka.KafkaProperties.IsolationLevel;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link KafkaProperties}.
+ *
+ * @author Stephane Nicoll
+ */
+class KafkaPropertiesTests {
+
+	@Test
+	void isolationLevelEnumConsistentWithKafkaVersion() {
+		org.apache.kafka.common.requests.IsolationLevel[] original = org.apache.kafka.common.requests.IsolationLevel
+				.values();
+		assertThat(original).extracting("name").containsExactly(IsolationLevel.READ_UNCOMMITTED.name(),
+				IsolationLevel.READ_COMMITTED.name());
+		assertThat(original).extracting("id").containsExactly(IsolationLevel.READ_UNCOMMITTED.id(),
+				IsolationLevel.READ_COMMITTED.id());
+		assertThat(original).hasSize(IsolationLevel.values().length);
+	}
+
+}