Firestore - Where exactly to put the @Exclude annotation?

Question

I am confused about where to put the @Exclude annotation for a field I don't want to have in my Cloud Firestore database.

Is it enough to only put it on the getter method? What effect does it have to also add it to the setter method or variable declaration?

In my example, I don't want to store the document ID, since this would be redundant:

public void loadNotes(View v) {
    notebookRef.get()
            .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
                @Override
                public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                    String data = "";

                    for (QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots) {
                        Note note = documentSnapshot.toObject(Note.class);
                        note.setDocumentId(documentSnapshot.getId());
                        String title = note.getTitle();
                        String description = note.getDescription();

                        data += "\nTitle: " + title + "Description: " + description;
                    }

                    textViewData.setText(data);
                }
            });
}

Model class:

public class Note {
private String documentId;
private String title;
private String description;

public Note() {
    //public no arg constructor necessary
}

public Note(String title, String description) {
    this.title = title;
    this.description = description;
}

@Exclude
public String getDocumentId() {
    return documentId;
}

public void setDocumentId(String documentId) {
    this.documentId = documentId;
}

public String getTitle() {
    return title;
}

public String getDescription() {
    return description;
}

}

Answer 1

Because you are using the private modifier for your fields inside your Note class, to exclude a property from a Cloud Firestore database you should place the @Exclude annotation before the corresponding getter.

@Exclude
public String getDocumentId() {return documentId;}

Is it enough to only put it on the getter method?

Yes, it is enough. If you have used the public modifier for your fields, to ignore a property you should have placed the @Exclude annotation before the property:

@Exclude 
public String documentId;

What effect does it have to also add it to the setter method or variable declaration?

No effect.