Optimized version of LinkBuilder.slash() method for identifiers

src/main/java/org/springframework/hateoas/server/LinkBuilder.java

@@ -38,6 +38,16 @@ public interface LinkBuilder {
 	 */
 	LinkBuilder slash(@Nullable Object object);
 
+	/**
+	 * Adds {@link String} representation of the given object as identifier of an item resource
+	 * from the current collection resource.
+	 *
+	 * This method is an optimized version of {@link #slash(Object)} mean to be used only for identifiers.
+	 *
+	 * @param id can be {@literal null}.
+	 */
+	LinkBuilder slashId(@Nullable Object id);
+
 	/**
 	 * Creates a URI of the link built by the current builder instance.
 	 *

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

@@ -32,6 +32,6 @@ public abstract class AbstractEntityLinks implements EntityLinks {
 	 */
 	@Override
 	public LinkBuilder linkForItemResource(Class<?> type, Object id) {
-		return linkFor(type).slash(id);
+		return linkFor(type).slashId(id);
 	}
 }

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

@@ -133,7 +133,7 @@ public Link linkToCollectionResource(Class<?> entity) {
 	 */
 	@Override
 	public Link linkToItemResource(Class<?> entity, Object id) {
-		return linkFor(entity).slash(id).withSelfRel();
+		return linkFor(entity).slashId(id).withSelfRel();
 	}
 
 	/*

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

@@ -76,7 +76,7 @@ protected LinkBuilderSupport(UriComponents components, List<Affordance> affordan
 	 */
 	public T slash(@Nullable Object object) {
 
-		object = object instanceof Optional ? ((Optional<?>) object).orElse(null) : object;
+		object = unwrapPotentialOptional(object);
 
 		if (object == null) {
 			return getThis();
@@ -97,6 +97,25 @@ public T slash(@Nullable Object object) {
 		return slash(UriComponentsBuilder.fromUriString(path).build(), false);
 	}
 
+	public T slashId(@Nullable Object id) {
+
+		id = unwrapPotentialOptional(id);
+
+		if (id == null) {
+			return getThis();
+		}
+
+		UriComponentsBuilder builder = UriComponentsBuilder.newInstance().uriComponents(this.components);
+		builder.pathSegment(encodePath(id));
+
+		return createNewInstance(builder.build(), affordances);
+	}
+
+	@Nullable
+	private Object unwrapPotentialOptional(@Nullable Object id) {
+		return id instanceof Optional ? ((Optional<?>) id).orElse(null) : id;
+	}
+
 	protected T slash(UriComponents components, boolean encoded) {
 
 		UriComponentsBuilder builder = UriComponentsBuilder.newInstance().uriComponents(this.components);

src/main/java/org/springframework/hateoas/server/mvc/RepresentationModelAssemblerSupport.java

@@ -95,7 +95,7 @@ protected D createModelWithId(Object id, T entity, Object... parameters) {
 		Assert.notNull(id, "Id must not be null!");
 
 		D instance = instantiateModel(entity);
-		instance.add(linkTo(this.controllerClass, parameters).slash(id).withSelfRel());
+		instance.add(linkTo(this.controllerClass, parameters).slashId(id).withSelfRel());
 		return instance;
 	}