remove deprecated validations

src/main/java/de/ul/swtp/modules/contactmanagement/Contact.java

@@ -36,10 +36,10 @@ public class Contact implements Serializable {
     @Email(regexp = "^.*@.*\\..*")
     private String email;
 
-    @javax.validation.constraints.NotBlank
+    @NotBlank
     private String firstName;
 
-    @javax.validation.constraints.NotBlank
+    @NotBlank
     private String lastName;
 
     @DateTimeFormat
@@ -51,7 +51,7 @@ public class Contact implements Serializable {
     @Digits(integer = 16, fraction = 0)
     private String phone;
 
-    //@javax.validation.constraints.NotBlank
+    //@NotBlank
     @OneToOne
     private Address address;
 

src/main/java/de/ul/swtp/system/User.java

@@ -7,7 +7,6 @@ import lombok.Data;
 import org.hibernate.annotations.LazyCollection;
 import org.hibernate.annotations.LazyCollectionOption;
 import org.hibernate.validator.constraints.Length;
-import org.hibernate.validator.constraints.NotBlank;
 
 import javax.persistence.*;
 import javax.validation.constraints.*;
@@ -38,7 +37,7 @@ public class User {
 
     //The regex ensures that only emails with top level domains are accepted (note that local email addresses are actually valid but of little use to us)
     @Email(regexp="^.*@.*\\..*")
-    @javax.validation.constraints.NotBlank
+    @NotBlank
     private String username;
 
     @Length(min=4, max=256)