Added serial version id to suppress warnings.

src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java

@@ -32,6 +32,10 @@ import javax.persistence.MappedSuperclass;
 @MappedSuperclass
 public class BaseEntity implements Serializable {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = -3856744164839586177L;
 	@Id
 	@GeneratedValue(strategy = GenerationType.IDENTITY)
 	private Integer id;

src/main/java/org/springframework/samples/petclinic/model/NamedEntity.java

@@ -28,6 +28,10 @@ import javax.persistence.MappedSuperclass;
 @MappedSuperclass
 public class NamedEntity extends BaseEntity {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = -1827620691768236760L;
 	@Column(name = "name")
 	private String name;
 

src/main/java/org/springframework/samples/petclinic/model/Person.java

@@ -27,6 +27,11 @@ import javax.validation.constraints.NotEmpty;
 @MappedSuperclass
 public class Person extends BaseEntity {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = -5934070342233945557L;
+
 	@Column(name = "first_name")
 	@NotEmpty
 	private String firstName;

src/main/java/org/springframework/samples/petclinic/owner/Owner.java

@@ -46,6 +46,11 @@ import org.springframework.samples.petclinic.model.Person;
 @Table(name = "owners")
 public class Owner extends Person {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = -916637073264067654L;
+
 	@Column(name = "address")
 	@NotEmpty
 	private String address;

src/main/java/org/springframework/samples/petclinic/owner/Pet.java

@@ -48,6 +48,11 @@ import org.springframework.samples.petclinic.visit.Visit;
 @Table(name = "pets")
 public class Pet extends NamedEntity {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 4327953478894967506L;
+
 	@Column(name = "birth_date")
 	@DateTimeFormat(pattern = "yyyy-MM-dd")
 	private LocalDate birthDate;

src/main/java/org/springframework/samples/petclinic/owner/PetType.java

@@ -27,4 +27,9 @@ import org.springframework.samples.petclinic.model.NamedEntity;
 @Table(name = "types")
 public class PetType extends NamedEntity {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = -7611995145056548231L;
+
 }

src/main/java/org/springframework/samples/petclinic/vet/Specialty.java

@@ -31,4 +31,9 @@ import org.springframework.samples.petclinic.model.NamedEntity;
 @Table(name = "specialties")
 public class Specialty extends NamedEntity implements Serializable {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 2199617339964039700L;
+
 }

src/main/java/org/springframework/samples/petclinic/vet/Vet.java

@@ -45,6 +45,10 @@ import org.springframework.samples.petclinic.model.Person;
 @Table(name = "vets")
 public class Vet extends Person {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 2216866745632621103L;
 	@ManyToMany(fetch = FetchType.EAGER)
 	@JoinTable(name = "vet_specialties", joinColumns = @JoinColumn(name = "vet_id"),
 			inverseJoinColumns = @JoinColumn(name = "specialty_id"))

src/main/java/org/springframework/samples/petclinic/visit/Visit.java

@@ -35,6 +35,11 @@ import org.springframework.samples.petclinic.model.BaseEntity;
 @Table(name = "visits")
 public class Visit extends BaseEntity {
 
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = -1400610663349907927L;
+
 	@Column(name = "visit_date")
 	@DateTimeFormat(pattern = "yyyy-MM-dd")
 	private LocalDate date;

src/test/java/org/springframework/samples/petclinic/owner/PetTypeFormatterTests.java

@@ -80,11 +80,21 @@ class PetTypeFormatterTests {
 	private List<PetType> makePetTypes() {
 		List<PetType> petTypes = new ArrayList<>();
 		petTypes.add(new PetType() {
+			/**
+			 * 
+			 */
+			private static final long serialVersionUID = 4182992965923515553L;
+
 			{
 				setName("Dog");
 			}
 		});
 		petTypes.add(new PetType() {
+			/**
+			 * 
+			 */
+			private static final long serialVersionUID = 1823182409934678856L;
+
 			{
 				setName("Bird");
 			}