Align HATEAOS sample with latest breaking API changes

See gh-15939

spring-boot-samples/spring-boot-sample-hateoas/src/main/java/sample/hateoas/web/CustomerController.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,10 +19,10 @@ package sample.hateoas.web;
 import sample.hateoas.domain.Customer;
 import sample.hateoas.domain.CustomerRepository;
 
-import org.springframework.hateoas.EntityLinks;
-import org.springframework.hateoas.ExposesResourceFor;
-import org.springframework.hateoas.Resource;
-import org.springframework.hateoas.Resources;
+import org.springframework.hateoas.CollectionModel;
+import org.springframework.hateoas.EntityModel;
+import org.springframework.hateoas.server.EntityLinks;
+import org.springframework.hateoas.server.ExposesResourceFor;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
@@ -47,16 +47,17 @@ public class CustomerController {
 	}
 
 	@GetMapping(produces = MediaType.APPLICATION_JSON_VALUE)
-	HttpEntity<Resources<Customer>> showCustomers() {
-		Resources<Customer> resources = new Resources<>(this.repository.findAll());
+	HttpEntity<CollectionModel<Customer>> showCustomers() {
+		CollectionModel<Customer> resources = new CollectionModel<>(
+				this.repository.findAll());
 		resources.add(this.entityLinks.linkToCollectionResource(Customer.class));
 		return new ResponseEntity<>(resources, HttpStatus.OK);
 	}
 
 	@GetMapping(path = "/{id}", produces = MediaType.APPLICATION_JSON_VALUE)
-	HttpEntity<Resource<Customer>> showCustomer(@PathVariable Long id) {
-		Resource<Customer> resource = new Resource<>(this.repository.findOne(id));
-		resource.add(this.entityLinks.linkToSingleResource(Customer.class, id));
+	HttpEntity<EntityModel<Customer>> showCustomer(@PathVariable Long id) {
+		EntityModel<Customer> resource = new EntityModel<>(this.repository.findOne(id));
+		resource.add(this.entityLinks.linkToItemResource(Customer.class, id));
 		return new ResponseEntity<>(resource, HttpStatus.OK);
 	}