diff --git a/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java b/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java
index 55b470e1e3eecf54369728983b41c9da46bb6af2..14603c1ff3f35b58efe937c7c4f59aedfe06d120 100644
--- a/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java
+++ b/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java
@@ -41,7 +41,7 @@ public class BaseEntity {
     }
 
     public boolean isNew() {
-        return (this.id == null);
+        return this.id == null;
     }
 
 }
diff --git a/src/main/java/org/springframework/samples/petclinic/web/OwnerController.java b/src/main/java/org/springframework/samples/petclinic/web/OwnerController.java
index 0ff2858d5a5e2aaa7094561c1e4e7cc2e2192c16..dfc8d0b7481edbb8fc9767e0eda887cbc96b08eb 100644
--- a/src/main/java/org/springframework/samples/petclinic/web/OwnerController.java
+++ b/src/main/java/org/springframework/samples/petclinic/web/OwnerController.java
@@ -42,6 +42,7 @@ import org.springframework.web.servlet.ModelAndView;
 @Controller
 public class OwnerController {
 
+    private static final String VIEWS_OWNER_CREATE_OR_UPDATE_FORM = "owners/createOrUpdateOwnerForm";
     private final ClinicService clinicService;
 
 
@@ -59,13 +60,13 @@ public class OwnerController {
     public String initCreationForm(Map<String, Object> model) {
         Owner owner = new Owner();
         model.put("owner", owner);
-        return "owners/createOrUpdateOwnerForm";
+        return VIEWS_OWNER_CREATE_OR_UPDATE_FORM;
     }
 
     @RequestMapping(value = "/owners/new", method = RequestMethod.POST)
     public String processCreationForm(@Valid Owner owner, BindingResult result) {
         if (result.hasErrors()) {
-            return "owners/createOrUpdateOwnerForm";
+            return VIEWS_OWNER_CREATE_OR_UPDATE_FORM;
         } else {
             this.clinicService.saveOwner(owner);
             return "redirect:/owners/" + owner.getId();
@@ -107,13 +108,13 @@ public class OwnerController {
     public String initUpdateOwnerForm(@PathVariable("ownerId") int ownerId, Model model) {
         Owner owner = this.clinicService.findOwnerById(ownerId);
         model.addAttribute(owner);
-        return "owners/createOrUpdateOwnerForm";
+        return VIEWS_OWNER_CREATE_OR_UPDATE_FORM;
     }
 
     @RequestMapping(value = "/owners/{ownerId}/edit", method = RequestMethod.POST)
     public String processUpdateOwnerForm(@Valid Owner owner, BindingResult result, @PathVariable("ownerId") int ownerId) {
         if (result.hasErrors()) {
-            return "owners/createOrUpdateOwnerForm";
+            return VIEWS_OWNER_CREATE_OR_UPDATE_FORM;
         } else {
             owner.setId(ownerId);
             this.clinicService.saveOwner(owner);
diff --git a/src/main/java/org/springframework/samples/petclinic/web/PetController.java b/src/main/java/org/springframework/samples/petclinic/web/PetController.java
index a944997595f7d3f79420532b83bfe2e2f6417cdd..6e2a59b9faafbde244a9ba6baa548efc91b21cb3 100644
--- a/src/main/java/org/springframework/samples/petclinic/web/PetController.java
+++ b/src/main/java/org/springframework/samples/petclinic/web/PetController.java
@@ -28,6 +28,7 @@ import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.bind.annotation.*;
 
 import javax.validation.Valid;
+
 import java.util.Collection;
 
 /**
@@ -39,6 +40,7 @@ import java.util.Collection;
 @RequestMapping("/owners/{ownerId}")
 public class PetController {
 
+    private static final String VIEWS_PETS_CREATE_OR_UPDATE_FORM = "pets/createOrUpdatePetForm";
     private final ClinicService clinicService;
 
     @Autowired
@@ -53,8 +55,7 @@ public class PetController {
 
     @ModelAttribute("owner")
     public Owner findOwner(@PathVariable("ownerId") int ownerId) {
-        Owner owner = this.clinicService.findOwnerById(ownerId);
-        return owner;
+        return this.clinicService.findOwnerById(ownerId);
     }
 
     @InitBinder("owner")
@@ -72,7 +73,7 @@ public class PetController {
         Pet pet = new Pet();
         owner.addPet(pet);
         model.put("pet", pet);
-        return "pets/createOrUpdatePetForm";
+        return VIEWS_PETS_CREATE_OR_UPDATE_FORM;
     }
 
     @RequestMapping(value = "/pets/new", method = RequestMethod.POST)
@@ -82,7 +83,7 @@ public class PetController {
         }
         if (result.hasErrors()) {
             model.put("pet", pet);
-            return "pets/createOrUpdatePetForm";
+            return VIEWS_PETS_CREATE_OR_UPDATE_FORM;
         } else {
             owner.addPet(pet);
             this.clinicService.savePet(pet);
@@ -94,14 +95,14 @@ public class PetController {
     public String initUpdateForm(@PathVariable("petId") int petId, ModelMap model) {
         Pet pet = this.clinicService.findPetById(petId);
         model.put("pet", pet);
-        return "pets/createOrUpdatePetForm";
+        return VIEWS_PETS_CREATE_OR_UPDATE_FORM;
     }
 
     @RequestMapping(value = "/pets/{petId}/edit", method = RequestMethod.POST)
     public String processUpdateForm(@Valid Pet pet, BindingResult result, Owner owner, ModelMap model) {
         if (result.hasErrors()) {
             model.put("pet", pet);
-            return "pets/createOrUpdatePetForm";
+            return VIEWS_PETS_CREATE_OR_UPDATE_FORM;
         } else {
             owner.addPet(pet);
             this.clinicService.savePet(pet);
diff --git a/src/main/java/org/springframework/samples/petclinic/web/PetValidator.java b/src/main/java/org/springframework/samples/petclinic/web/PetValidator.java
index d889d1af6a7db7c764b2df996eb37d6f96a3f959..3c04793b9c438e46479ad0397186c8cb3535753b 100644
--- a/src/main/java/org/springframework/samples/petclinic/web/PetValidator.java
+++ b/src/main/java/org/springframework/samples/petclinic/web/PetValidator.java
@@ -31,23 +31,25 @@ import org.springframework.validation.Validator;
  */
 public class PetValidator implements Validator {
 
+    private static final String REQUIRED = "required";
+
     @Override
     public void validate(Object obj, Errors errors) {
         Pet pet = (Pet) obj;
         String name = pet.getName();
         // name validation
         if (!StringUtils.hasLength(name)) {
-            errors.rejectValue("name", "required", "required");
+            errors.rejectValue("name", REQUIRED, REQUIRED);
         }
 
         // type validation
         if (pet.isNew() && pet.getType() == null) {
-            errors.rejectValue("type", "required", "required");
+            errors.rejectValue("type", REQUIRED, REQUIRED);
         }
 
         // birth date validation
         if (pet.getBirthDate() == null) {
-            errors.rejectValue("birthDate", "required", "required");
+            errors.rejectValue("birthDate", REQUIRED, REQUIRED);
         }
     }
 
diff --git a/src/test/java/org/springframework/samples/petclinic/service/AbstractClinicServiceTests.java b/src/test/java/org/springframework/samples/petclinic/service/AbstractClinicServiceTests.java
index 469c24b47e1a28be24031ba886233396dd12384c..82786a2c8a88e775cce06f94e11f9323f2ddb30f 100644
--- a/src/test/java/org/springframework/samples/petclinic/service/AbstractClinicServiceTests.java
+++ b/src/test/java/org/springframework/samples/petclinic/service/AbstractClinicServiceTests.java
@@ -62,7 +62,7 @@ public abstract class AbstractClinicServiceTests {
         assertThat(owners.size()).isEqualTo(2);
 
         owners = this.clinicService.findOwnerByLastName("Daviss");
-        assertThat(owners.isEmpty());
+        assertThat(owners.isEmpty()).isTrue();
     }
 
     @Test