#1442 - Exposes consumed media types on affordances.

InputPayloadMetadata now captures and exposes supported media types. SpringAffordanceBuilder obtains them from the newly introduced API available on MappingDiscoverer.

src/main/java/org/springframework/hateoas/AffordanceModel.java

@@ -257,16 +257,29 @@ public abstract class AffordanceModel {
 		 * @return will never be {@literal null}.
 		 * @since 1.3
 		 */
-		InputPayloadMetadata withMediaType(@Nullable MediaType mediaType);
+		InputPayloadMetadata withMediaTypes(List<MediaType> mediaType);
 
 		/**
 		 * Returns the {@link MediaType} that the payload requires.
 		 *
-		 * @return can be {@literal null}.
+		 * @return will never be {@literal null}.
 		 * @since 1.3
 		 */
+		List<MediaType> getMediaTypes();
+
+		/**
+		 * Returns the primary {@link MediaType} expected for the input. That is, from {@link #getMediaTypes()} the first
+		 * one, if available.
+		 *
+		 * @return can be {@literal null}.
+		 */
 		@Nullable
-		MediaType getMediaType();
+		default MediaType getPrimaryMediaType() {
+
+			List<MediaType> mediaTypes = getMediaTypes();
+
+			return mediaTypes.isEmpty() ? null : mediaTypes.get(0);
+		}
 	}
 
 	/**
@@ -277,15 +290,15 @@ public abstract class AffordanceModel {
 	private static class DelegatingInputPayloadMetadata implements InputPayloadMetadata {
 
 		private final PayloadMetadata metadata;
-		private final MediaType mediaType;
+		private final List<MediaType> mediaTypes;
 
 		public static DelegatingInputPayloadMetadata of(PayloadMetadata metadata) {
-			return new DelegatingInputPayloadMetadata(metadata, null);
+			return new DelegatingInputPayloadMetadata(metadata, Collections.emptyList());
 		}
 
-		private DelegatingInputPayloadMetadata(PayloadMetadata metadata, MediaType mediaType) {
+		private DelegatingInputPayloadMetadata(PayloadMetadata metadata, List<MediaType> mediaTypes) {
 			this.metadata = metadata;
-			this.mediaType = mediaType;
+			this.mediaTypes = mediaTypes;
 		}
 
 		/*
@@ -326,20 +339,20 @@ public abstract class AffordanceModel {
 
 		/*
 		 * (non-Javadoc)
-		 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#withMediaType(org.springframework.http.MediaType)
+		 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#withMediaTypes(java.util.List)
 		 */
 		@Override
-		public InputPayloadMetadata withMediaType(MediaType mediaType) {
-			return new DelegatingInputPayloadMetadata(metadata, mediaType);
+		public InputPayloadMetadata withMediaTypes(List<MediaType> mediaTypes) {
+			return new DelegatingInputPayloadMetadata(metadata, mediaTypes);
 		}
 
 		/*
 		 * (non-Javadoc)
-		 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#getMediaType()
+		 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#getMediaTypes()
 		 */
 		@Override
-		public MediaType getMediaType() {
-			return mediaType;
+		public List<MediaType> getMediaTypes() {
+			return mediaTypes;
 		}
 
 		/*

src/main/java/org/springframework/hateoas/mediatype/Affordances.java

@@ -215,8 +215,17 @@ public class Affordances implements AffordanceOperations {
 		 * @see org.springframework.hateoas.mediatype.ConfigurableAffordance#withInputMediaType(org.springframework.http.MediaType)
 		 */
 		@Override
-		public AffordanceBuilder withInputMediaType(@Nullable MediaType inputMediaType) {
-			return withInput(inputMetdata.withMediaType(inputMediaType));
+		public ConfigurableAffordance withInputMediaType(MediaType inputMediaType) {
+			return withInputMediaTypes(Arrays.asList(inputMediaType));
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.hateoas.mediatype.ConfigurableAffordance#withInputMediaTypes(java.util.List)
+		 */
+		@Override
+		public ConfigurableAffordance withInputMediaTypes(List<MediaType> inputMediaTypes) {
+			return withInput(inputMetdata.withMediaTypes(inputMediaTypes));
 		}
 
 		/*

src/main/java/org/springframework/hateoas/mediatype/ConfigurableAffordance.java

@@ -111,10 +111,18 @@ public interface ConfigurableAffordance extends AffordanceOperations {
 	/**
 	 * Registers the input to expect to be of the given {@link MediaType}.
 	 *
-	 * @param inputMediaType
-	 * @return
+	 * @param inputMediaType can be {@literal null}.
+	 * @return will never be {@literal null}.
 	 */
-	ConfigurableAffordance withInputMediaType(@Nullable MediaType inputMediaType);
+	ConfigurableAffordance withInputMediaType(MediaType inputMediaType);
+
+	/**
+	 * Registers the given {@link MediaType}s as input payload media types.
+	 *
+	 * @param inputMediaTypes must not be {@literal null}.
+	 * @return will never be {@literal null}.
+	 */
+	ConfigurableAffordance withInputMediaTypes(List<MediaType> inputMediaTypes);
 
 	/**
 	 * Replaces the current {@link QueryParameter} list with the given ones.

src/main/java/org/springframework/hateoas/mediatype/TypeBasedPayloadMetadata.java

@@ -16,6 +16,7 @@
 package org.springframework.hateoas.mediatype;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.SortedMap;
 import java.util.TreeMap;
@@ -28,7 +29,7 @@ import org.springframework.hateoas.AffordanceModel.InputPayloadMetadata;
 import org.springframework.hateoas.AffordanceModel.Named;
 import org.springframework.hateoas.AffordanceModel.PropertyMetadata;
 import org.springframework.http.MediaType;
-import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * {@link InputPayloadMetadata} implementation based on a Java type.
@@ -39,19 +40,23 @@ class TypeBasedPayloadMetadata implements InputPayloadMetadata {
 
 	private final ResolvableType type;
 	private final SortedMap<String, PropertyMetadata> properties;
-	private final @Nullable MediaType mediaType;
+	private final List<MediaType> mediaTypes;
 
 	TypeBasedPayloadMetadata(ResolvableType type, Stream<PropertyMetadata> properties) {
 		this(type, new TreeMap<>(
-				properties.collect(Collectors.toMap(PropertyMetadata::getName, Function.identity()))), null);
+				properties.collect(Collectors.toMap(PropertyMetadata::getName, Function.identity()))), Collections.emptyList());
 	}
 
 	TypeBasedPayloadMetadata(ResolvableType type, SortedMap<String, PropertyMetadata> properties,
-			@Nullable MediaType mediaType) {
+			List<MediaType> mediaTypes) {
+
+		Assert.notNull(type, "Type must not be null!");
+		Assert.notNull(properties, "Properties must not be null!");
+		Assert.notNull(mediaTypes, "Media types must not be null!");
 
 		this.type = type;
 		this.properties = properties;
-		this.mediaType = mediaType;
+		this.mediaTypes = mediaTypes;
 	}
 
 	/*
@@ -93,20 +98,19 @@ class TypeBasedPayloadMetadata implements InputPayloadMetadata {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#withMediaType(org.springframework.http.MediaType)
+	 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#withMediaTypes(java.util.List)
 	 */
 	@Override
-	public InputPayloadMetadata withMediaType(@Nullable MediaType mediaType) {
-		return new TypeBasedPayloadMetadata(type, properties, mediaType);
+	public InputPayloadMetadata withMediaTypes(List<MediaType> mediaTypes) {
+		return new TypeBasedPayloadMetadata(type, properties, mediaTypes);
 	}
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#getMediaType()
+	 * @see org.springframework.hateoas.AffordanceModel.InputPayloadMetadata#getMediaTypes()
 	 */
-	@Nullable
 	@Override
-	public MediaType getMediaType() {
-		return mediaType;
+	public List<MediaType> getMediaTypes() {
+		return mediaTypes;
 	}
 }

src/main/java/org/springframework/hateoas/server/core/AnnotationMappingDiscoverer.java

@@ -21,13 +21,16 @@ import static org.springframework.core.annotation.AnnotationUtils.*;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.bind.annotation.RequestMethod;
@@ -153,6 +156,21 @@ public class AnnotationMappingDiscoverer implements MappingDiscoverer {
 		return requestMethodNames;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.server.core.MappingDiscoverer#getConsumes(java.lang.reflect.Method)
+	 */
+	@Override
+	public List<MediaType> getConsumes(Method method) {
+
+		Annotation annotation = findMergedAnnotation(method, annotationType);
+		String[] mediaTypes = (String[]) getValue(annotation, "consumes");
+
+		return mediaTypes == null
+				? Collections.emptyList()
+				: Arrays.stream(mediaTypes).map(MediaType::parseMediaType).collect(Collectors.toList());
+	}
+
 	private String[] getMappingFrom(@Nullable Annotation annotation) {
 
 		if (annotation == null) {

src/main/java/org/springframework/hateoas/server/core/CachingMappingDiscoverer.java

@@ -17,9 +17,11 @@ package org.springframework.hateoas.server.core;
 
 import java.lang.reflect.Method;
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
 import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.StringUtils;
@@ -93,6 +95,15 @@ public class CachingMappingDiscoverer implements MappingDiscoverer {
 		return METHODS.computeIfAbsent(key(type, method), __ -> delegate.getRequestMethod(type, method));
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.server.core.MappingDiscoverer#getConsumes(java.lang.reflect.Method)
+	 */
+	@Override
+	public List<MediaType> getConsumes(Method method) {
+		return delegate.getConsumes(method);
+	}
+
 	private static String key(Class<?> type, @Nullable Method method) {
 
 		StringBuilder builder = new StringBuilder(type.getName());

src/main/java/org/springframework/hateoas/server/core/MappingDiscoverer.java

@@ -17,8 +17,10 @@ package org.springframework.hateoas.server.core;
 
 import java.lang.reflect.Method;
 import java.util.Collection;
+import java.util.List;
 
 import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 
 /**
@@ -68,4 +70,13 @@ public interface MappingDiscoverer {
 	 * @return
 	 */
 	Collection<HttpMethod> getRequestMethod(Class<?> type, Method method);
+
+	/**
+	 * Returns the {@link MediaType}s supported for consumption.
+	 *
+	 * @param method must not be {@literal null}.
+	 * @return can be {@literal null}.
+	 * @since 1.3
+	 */
+	List<MediaType> getConsumes(Method method);
 }

src/main/java/org/springframework/hateoas/server/core/PropertyResolvingMappingDiscoverer.java

@@ -17,8 +17,10 @@ package org.springframework.hateoas.server.core;
 
 import java.lang.reflect.Method;
 import java.util.Collection;
+import java.util.List;
 
 import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.web.context.ContextLoader;
@@ -80,6 +82,15 @@ class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
 		return delegate.getRequestMethod(type, method);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.server.core.MappingDiscoverer#getConsumes(java.lang.reflect.Method)
+	 */
+	@Override
+	public List<MediaType> getConsumes(Method method) {
+		return delegate.getConsumes(method);
+	}
+
 	@Nullable
 	private static String resolveProperties(@Nullable String mapping) {
 

src/main/java/org/springframework/hateoas/server/core/SpringAffordanceBuilder.java

@@ -72,6 +72,7 @@ public class SpringAffordanceBuilder {
 						.withOutput(outputType) //
 						.withParameters(queryMethodParameters) //
 						.withName(methodName) //
+						.withInputMediaTypes(discoverer.getConsumes(method)) //
 						.build() //
 						.stream()) //
 				.collect(Collectors.toList());

src/test/java/org/springframework/hateoas/server/core/AnnotationMappingDiscovererUnitTest.java

@@ -20,6 +20,7 @@ import static org.assertj.core.api.Assertions.*;
 import java.lang.reflect.Method;
 
 import org.junit.jupiter.api.Test;
+import org.springframework.http.MediaType;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 
@@ -160,6 +161,16 @@ class AnnotationMappingDiscovererUnitTest {
 		assertThat(discoverer.getMapping(method)).isEqualTo("/type/foo/{bar}");
 	}
 
+	@Test // #1442
+	void exposesConsumesClause() throws Exception {
+
+		Method method = MyController.class.getMethod("mappingWithConsumesClause");
+		assertThat(discoverer.getConsumes(method)).containsExactly(MediaType.APPLICATION_JSON);
+
+		method = MyController.class.getMethod("method");
+		assertThat(discoverer.getConsumes(method)).isEmpty();
+	}
+
 	@RequestMapping("/type")
 	interface MyController {
 
@@ -174,6 +185,9 @@ class AnnotationMappingDiscovererUnitTest {
 
 		@RequestMapping("/foo/{bar:[ABC]{1}}")
 		void mappingWithMatchingExpression();
+
+		@RequestMapping(path = "/path", consumes = "application/json")
+		void mappingWithConsumesClause();
 	}
 
 	interface ControllerWithoutTypeLevelMapping {