#831 - Introduce null handling.

src/main/java/org/springframework/hateoas/client/Rels.java

@@ -19,6 +19,7 @@ import java.util.Optional;
 
 import org.springframework.hateoas.Link;
 import org.springframework.http.MediaType;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 import com.jayway.jsonpath.JsonPath;
@@ -60,7 +61,7 @@ class Rels {
 		 * @param mediaType
 		 * @return
 		 */
-		Optional<Link> findInResponse(String representation, MediaType mediaType);
+		Optional<Link> findInResponse(@Nullable String representation, @Nullable MediaType mediaType);
 	}
 
 	/**
@@ -141,7 +142,7 @@ class Rels {
 		 * @see org.springframework.hateoas.client.Rels.Rel#findInResponse(java.lang.String, org.springframework.http.MediaType)
 		 */
 		@Override
-		public Optional<Link> findInResponse(String representation, MediaType mediaType) {
+		public Optional<Link> findInResponse(@Nullable String representation, @Nullable MediaType mediaType) {
 			return Optional.of(new Link(JsonPath.read(representation, jsonPath).toString(), rel));
 		}
 	}

src/main/java/org/springframework/hateoas/client/Traverson.java

@@ -40,6 +40,7 @@ import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.lang.Nullable;
 import org.springframework.plugin.core.PluginRegistry;
 import org.springframework.util.Assert;
 import org.springframework.web.client.RestOperations;
@@ -139,7 +140,7 @@ public class Traverson {
 	 * @param operations
 	 * @return
 	 */
-	public Traverson setRestOperations(RestOperations operations) {
+	public Traverson setRestOperations(@Nullable RestOperations operations) {
 
 		this.operations = operations == null //
 				? createDefaultTemplate(this.mediaTypes) //
@@ -155,7 +156,7 @@ public class Traverson {
 	 * @param discoverer can be {@literal null}.
 	 * @return
 	 */
-	public Traverson setLinkDiscoverers(List<? extends LinkDiscoverer> discoverer) {
+	public Traverson setLinkDiscoverers(@Nullable List<? extends LinkDiscoverer> discoverer) {
 
 		List<? extends LinkDiscoverer> defaultedDiscoverers = discoverer == null //
 				? DEFAULTS.getLinkDiscoverers(mediaTypes) //
@@ -282,6 +283,7 @@ public class Traverson {
 		 * @param type must not be {@literal null}.
 		 * @return
 		 */
+		@Nullable
 		public <T> T toObject(Class<T> type) {
 
 			Assert.notNull(type, "Target type must not be null!");
@@ -299,6 +301,7 @@ public class Traverson {
 		 * @param type must not be {@literal null}.
 		 * @return
 		 */
+		@Nullable
 		public <T> T toObject(ParameterizedTypeReference<T> type) {
 
 			Assert.notNull(type, "Target type must not be null!");

src/main/java/org/springframework/hateoas/client/package-info.java

@@ -1,5 +1,7 @@
 /**
  * Client side support.
  */
+@NonNullApi
 package org.springframework.hateoas.client;
 
+import org.springframework.lang.NonNullApi;