#1974 - Improve default LinkRelationProvider setup to also consider @relation.

RepositoryRestConfiguration now defaults the LinkRelationProvider instance to a delegating one considering both AnnotationLinkRelationProvider and EvoLinkRelationProvider so that @relation annotations on entity types.

Author: odrotbohm

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/config/RepositoryRestConfiguration.java

@@ -33,6 +33,8 @@
 import org.springframework.data.rest.core.support.EntityLookup;
 import org.springframework.hateoas.MediaTypes;
 import org.springframework.hateoas.server.LinkRelationProvider;
+import org.springframework.hateoas.server.core.AnnotationLinkRelationProvider;
+import org.springframework.hateoas.server.core.DelegatingLinkRelationProvider;
 import org.springframework.hateoas.server.core.EvoInflectorLinkRelationProvider;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
@@ -103,6 +105,10 @@ public RepositoryRestConfiguration(ProjectionDefinitionConfiguration projectionC
 		this.enumTranslationConfiguration = enumTranslationConfiguration;
 		this.entityLookupConfiguration = new EntityLookupConfiguration();
 		this.exposureConfiguration = new ExposureConfiguration();
+
+		this.relProvider = new DelegatingLinkRelationProvider( //
+				new AnnotationLinkRelationProvider(), //
+				new EvoInflectorLinkRelationProvider());
 	}
 
 	/**

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/RepositoryRestConfigurationUnitTests.java

@@ -29,6 +29,8 @@
 import org.springframework.data.rest.core.config.RepositoryRestConfiguration;
 import org.springframework.data.rest.core.domain.Profile;
 import org.springframework.data.rest.core.domain.ProfileRepository;
+import org.springframework.hateoas.LinkRelation;
+import org.springframework.hateoas.server.core.Relation;
 import org.springframework.http.MediaType;
 import org.springframework.web.cors.CorsConfiguration;
 
@@ -136,4 +138,15 @@ public void configuresCorsProcessing() {
 	public void rejectsNullRelProvider() {
 		assertThatExceptionOfType(IllegalArgumentException.class).isThrownBy(() -> configuration.setRelProvider(null));
 	}
+
+	@Test // #1974
+	public void considersAtRelationOnTypesByDefault() {
+		assertThat(configuration.getRelProvider().getItemResourceRelFor(Sample.class))
+				.isEqualTo(LinkRelation.of("something"));
+	}
+
+	@Relation("something")
+	static class Sample {
+
+	}
 }