@Transient not working with @ElementCollection on same field

Question

I have class like this

{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @ElementCollection
    @Transient
    @JsonProperty("custom_fields")
    private Map<String, String> customFields;

    private String description;
}

However I dont want 'customFields' field to store in the database. So I have used @Transient annotation with it. But it is creating new table and creating foreign key. And value of 'customFields' is getting stored in that table. I guess it is happening because of @ElementCollection annotation. If I remove @ElementCollection I am getting this exception: Could not determine type for: java.util.Map, at table. However @Transient works perfectly if Field is not a collection.

How can I achieve this ? I want that field in class but don't want to store it in database.