import org.springframework.format.annotation.DateTimeFormat;
import javax.validation.constraints.NotNull;
import java.util.Date;

public class HourTracker {
@NotNull(message = "start time cannot be null")
@DateTimeFormat(pattern = "hh:mma")
private Date startTime;
@NotNull(message = "end time cannot be null")
@DateTimeFormat(pattern = "hh:mma")
private Date endTime;

//getters and setters
}