Go 1.16: retract directive
Retract specific versions of your modules
From the Go documentation for the retract directive:
A retract directive indicates that a version or range of versions of the module defined by go.mod should not be depended upon. A retract directive is useful when a version was published prematurely or a severe problem was discovered after the version was published.
How to use:
This feature does not require anything special to be used. The IDE recognizes it automatically.