GH-1285: Fix @RabbitListener with @headers

Resolves #1285

* Add gradle plugin repo.

**cherry-pick to 2.2.x**
# Conflicts:
#	build.gradle
#	spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/adapter/MessagingMessageListenerAdapter.java

build.gradle

@@ -1,6 +1,7 @@
 buildscript {
 	ext.kotlinVersion = '1.3.72'
 	repositories {
+		maven { url 'https://plugins.gradle.org/m2' }
 		maven { url 'https://repo.spring.io/plugins-release' }
 	}
 	dependencies {

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/listener/adapter/MessagingMessageListenerAdapter.java

@@ -35,6 +35,7 @@
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.handler.annotation.Header;
+import org.springframework.messaging.handler.annotation.Headers;
 import org.springframework.messaging.handler.annotation.Payload;
 import org.springframework.messaging.support.MessageBuilder;
 import org.springframework.remoting.support.RemoteInvocationResult;
@@ -337,17 +338,16 @@ private Type determineInferredType() {
 				 * We're looking for a single parameter, or one annotated with @Payload.
 				 * We ignore parameters with type Message because they are not involved with conversion.
 				 */
-				boolean isHeader = methodParameter.hasParameterAnnotation(Header.class);
+				boolean isHeaderOrHeaders = methodParameter.hasParameterAnnotation(Header.class)
+						|| methodParameter.hasParameterAnnotation(Headers.class);
 				boolean isPayload = methodParameter.hasParameterAnnotation(Payload.class);
-				if (isHeader && isPayload) {
-					if (MessagingMessageListenerAdapter.this.logger.isWarnEnabled()) {
-						MessagingMessageListenerAdapter.this.logger.warn(this.method.getName()
-							+ ": Cannot annotate a parameter with both @Header and @Payload; "
-							+ "ignored for payload conversion");
-					}
+				if (isHeaderOrHeaders && isPayload && MessagingMessageListenerAdapter.this.logger.isWarnEnabled()) {
+					MessagingMessageListenerAdapter.this.logger.warn(this.method.getName()
+						+ ": Cannot annotate a parameter with both @Header and @Payload; "
+						+ "ignored for payload conversion");
 				}
 				if (isEligibleParameter(methodParameter)
-						&& (!isHeader || isPayload) && !(isHeader && isPayload)) {
+						&& (!isHeaderOrHeaders || isPayload) && !(isHeaderOrHeaders && isPayload)) {
 
 					if (genericParameterType == null) {
 						genericParameterType = extractGenericParameterTypFromMethodParameter(methodParameter);

spring-rabbit/src/test/java/org/springframework/amqp/rabbit/listener/adapter/MessagingMessageListenerAdapterTests.java

@@ -28,6 +28,7 @@
 import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 import org.junit.jupiter.api.BeforeEach;
@@ -39,8 +40,10 @@
 import org.springframework.amqp.support.AmqpHeaders;
 import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
 import org.springframework.amqp.support.converter.SimpleMessageConverter;
+import org.springframework.amqp.utils.test.TestUtils;
 import org.springframework.beans.factory.support.StaticListableBeanFactory;
 import org.springframework.messaging.Message;
+import org.springframework.messaging.handler.annotation.Headers;
 import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
 import org.springframework.messaging.support.MessageBuilder;
@@ -192,6 +195,13 @@ public void genericMessageTest1() throws Exception {
 		assertThat(this.sample.payload.getClass()).isEqualTo(LinkedHashMap.class);
 	}
 
+	@Test
+	void headers() throws Exception {
+		MessagingMessageListenerAdapter listener = getSimpleInstance("withHeaders", Foo.class, Map.class);
+		assertThat(TestUtils.getPropertyValue(listener, "messagingMessageConverter.inferredArgumentType"))
+				.isEqualTo(Foo.class);
+	}
+
 	@Test
 	public void genericMessageTest2() throws Exception {
 		org.springframework.amqp.core.Message message = MessageTestUtils.createTextMessage("{ \"foo\" : \"bar\" }");
@@ -378,6 +388,10 @@ public String failWithReturn(Integer input) {
 			throw new IllegalArgumentException("Expected test exception");
 		}
 
+		@SuppressWarnings("unused")
+		public void withHeaders(Foo foo, @Headers Map<String, Object> headers) {
+		}
+
 	}
 
 	private static class Foo {