Minor changes

src/main/java/io/fp/campus/Faculty.java

@@ -21,11 +21,13 @@ public class Faculty {
     }
 
     public void addProfessor(Professor professor) {
-        profs.add(professor);
+        if (!profs.contains(professor))
+            profs.add(professor);
     }
 
     public void addAssistent(Assistent assistent) {
-        assis.add(assistent);
+        if (!assis.contains(assistent))
+            assis.add(assistent);
     }
 
     public ArrayList<Professor> getProfs() {

src/main/java/io/fp/campus/Professor.java

@@ -50,4 +50,12 @@ public class Professor {
     public String toString() {
         return name;
     }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
 }
\ No newline at end of file

src/test/java/io/fp/campus/AppTest.java

-/*
- * This Java source file was generated by the Gradle 'init' task.
- */
-package io.fp.campus;
-
-
-class AppTest {
-    
-}