Upgraded Kotlin plugin

spring-cloud-function-context/pom.xml

@@ -13,9 +13,6 @@
 		<artifactId>spring-cloud-function-parent</artifactId>
 		<version>2.0.0.BUILD-SNAPSHOT</version>
 	</parent>
-	<properties>
-		<kotlin.version>1.2.61</kotlin.version>
-	</properties>
 
 	<dependencies>
 		<dependency>
@@ -66,7 +63,7 @@
 			<plugin>
 				<artifactId>kotlin-maven-plugin</artifactId>
 				<groupId>org.jetbrains.kotlin</groupId>
-				<version>${kotlin.version}</version>
+				<version>1.2.71</version>
 				<executions>
 					<execution>
 						<id>compile</id>

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/util/HeaderUtils.java

@@ -71,10 +71,6 @@ public class HeaderUtils {
 		return result;
 	}
 
-	private static Collection<?> multi(Object value) {
-		return value instanceof Collection ? (Collection<?>) value : Arrays.asList(value);
-	}
-
 	public static MessageHeaders fromHttp(HttpHeaders headers) {
 		Map<String, Object> map = new LinkedHashMap<>();
 		for (String name : headers.keySet()) {
@@ -86,4 +82,8 @@ public class HeaderUtils {
 		}
 		return new MessageHeaders(map);
 	}
+
+	private static Collection<?> multi(Object value) {
+		return value instanceof Collection ? (Collection<?>) value : Arrays.asList(value);
+	}
 }