lockAttribute() not disabling field in upgraded magento 2.1.5

[deep1086]

Hi,

We have upgraded Magento 2.0.6 to 2.1.5, where we have used lockAttribute()  in observer to lock product default attribute whereas it is not saving field which is fine but it displaying as editable field for which we need solution and suggestion.

Please give some suggestions.

Thanks.

[deep1086]

I have used Modifier and achieved disable product attribute.