Added Setter for Professor ID

src/main/java/org/example/Professor.java

@@ -17,4 +17,8 @@ public class Professor {
     public String getProfessorID() {
         return professorID;
     }
+
+    public void setProfessorID(String professorID) {
+        this.professorID = professorID;
+    }
 }