（projid    null  || s.FKProjectId == projid）&& （Environment    null  || s.DomainEnvironment == Environment）

var exp = ProjectDomains.Where(s => s.FKProjectId == projid && s.DomainEnvironment == Environment )
In above linq query "projid ","Environment " values are passing from user .if either one of the values passed null.I want the filter with passed parameter only neglecting null parameter.
How can i achieve this?

(projid is null || s.FKProjectId == projid) && (Environment is null || s.DomainEnvironment == Environment)