Add function getNextDeadline()

src/main/java/ru/ulstu/grant/model/Grant.java

@@ -10,11 +10,7 @@ import ru.ulstu.user.model.User;
 
 import javax.persistence.*;
 import javax.validation.constraints.NotNull;
-import java.util.ArrayList;
-import java.util.Date;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 @Entity
 public class Grant extends BaseEntity  {
@@ -103,4 +99,13 @@ public class Grant extends BaseEntity  {
     public void setProject(Project project) {
         this.project = project;
     }
+
+    public Optional<Deadline> getNextDeadline() {
+        return deadlines
+                .stream()
+                .filter(deadline -> deadline.getDate() != null)
+                .sorted(Comparator.comparing(Deadline::getDate))
+                .filter(d -> d.getDate().after(new Date()))
+                .findFirst();
+    }
 }