StringConverter

@FacesConverter(forClass = String.class)
public class StringConverter implements Converter{

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String value) throws ConverterException {
        if (component instanceof HtmlInputText || component instanceof HtmlInputTextarea) {
            return (value != null) ? StringUtils.trimToNull(value) : null;
        }
        return value;
    }

    @Override
    public String getAsString(FacesContext context, UIComponent component, Object value) throws ConverterException {
        return (value != null) ? value.toString() : null;
    }
}