OZG-6867 OZG-6905 add relation to organisationseinheiten

src/main/java/de/ozgcloud/admin/organisationseinheit/OrganisationsEinheitController.java

+package de.ozgcloud.admin.organisationseinheit;
+
+import org.springframework.hateoas.CollectionModel;
+import org.springframework.hateoas.EntityModel;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import lombok.RequiredArgsConstructor;
+
+@RestController
+@RequestMapping(OrganisationsEinheitController.PATH)
+@RequiredArgsConstructor
+class OrganisationsEinheitController {
+
+	static final String PATH = "/api/organisationseinheits"; // NOSONAR
+
+	public CollectionModel<EntityModel<OrganisationsEinheit>> getAll(){
+		throw new UnsupportedOperationException("Not implemented yet");
+	}
+}

src/main/java/de/ozgcloud/admin/organisationseinheit/OrganisationsEinheitRootProcessor.java

+package de.ozgcloud.admin.organisationseinheit;
+
+import static org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.*;
+
+import org.springframework.hateoas.EntityModel;
+import org.springframework.hateoas.server.RepresentationModelProcessor;
+import org.springframework.stereotype.Component;
+
+import de.ozgcloud.admin.Root;
+
+@Component
+class OrganisationsEinheitRootProcessor  implements RepresentationModelProcessor<EntityModel<Root>> {
+
+	static final String REL_ORGANISATIONS_EINHEITEN = "organisationsEinheiten";
+
+	@Override
+	public EntityModel<Root> process(EntityModel<Root> model) {
+		return model.add(linkTo(methodOn(OrganisationsEinheitController.class).getAll()).withRel(REL_ORGANISATIONS_EINHEITEN));
+	}
+}

src/test/java/de/ozgcloud/admin/organisationseinheit/OrganisationsEinheitRootProcessorTest.java

+package de.ozgcloud.admin.organisationseinheit;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
+import org.springframework.hateoas.EntityModel;
+import org.springframework.hateoas.Link;
+
+import de.ozgcloud.admin.RootTestFactory;
+
+class OrganisationsEinheitRootProcessorTest {
+
+	@InjectMocks
+	private OrganisationsEinheitRootProcessor organisationsEinheitRootProcessor;
+
+	@Nested
+	class TestProcess {
+
+		@Nested
+		class OrganisationsEinheitenLinkRelation {
+
+			@Test
+			void shouldExists() {
+				var model = organisationsEinheitRootProcessor.process(EntityModel.of(RootTestFactory.create()));
+
+				assertThat(model.getLink(OrganisationsEinheitRootProcessor.REL_ORGANISATIONS_EINHEITEN)).isNotEmpty();
+			}
+
+			@Test
+			void shouldHaveHref() {
+				var model = organisationsEinheitRootProcessor.process(EntityModel.of(RootTestFactory.create()));
+
+				assertThat(model.getLink(OrganisationsEinheitRootProcessor.REL_ORGANISATIONS_EINHEITEN))
+						.get()
+						.extracting(Link::getHref)
+						.isEqualTo(OrganisationsEinheitController.PATH);
+			}
+		}
+
+	}
+
+}
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