class PresentFilter extends AbstractFilter {

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        PresentFilter that = (PresentFilter) o;

        if (attribute != null ? !attribute.equals(that.attribute) : that.attribute != null) return false;

        return true;
    }

    public  PresentFilter(String attribute);

}