prow/config/tide.go
func (cp *TideContextPolicy) IsOptional(c string) bool {
	if sets.NewString(cp.OptionalContexts...).Has(c) {
		return true
	}
	if sets.NewString(cp.RequiredContexts...).Has(c) {
		return false
	}
	// assume if we're asking that the context is present on the PR
	if sets.NewString(cp.RequiredIfPresentContexts...).Has(c) {
		return false
	}
	if cp.SkipUnknownContexts != nil && *cp.SkipUnknownContexts {
		return true
	}
	return false
}
func (cp *TideContextPolicy) IsOptional(c string) bool {
	if sets.NewString(cp.OptionalContexts...).Has(c) {
		return true
	}
	if sets.NewString(cp.RequiredContexts...).Has(c) {
		return false
	}
	// assume if we're asking that the context is present on the PR
	if sets.NewString(cp.RequiredIfPresentContexts...).Has(c) {
		return false
	}
	if cp.SkipUnknownContexts != nil && *cp.SkipUnknownContexts {
		return true
	}
	return false
}
// IsOptional checks whether a context can be ignored.
// Will return true if
// - context is registered as optional
// - required contexts are registered and the context provided is not required
// Will return false otherwise. Every context is required.