encoding/jsonsschema: use openAPI not vset(VersionOpenAPI)

This is equivalent and slightly more concise (and it's also
good to be consistent with the other places an openAPI
version is used).

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I69eff1310409e465eac03da3409030918e4e4908
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1200897
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: rogpeppe

Diff for: encoding/jsonschema/constraints.go

@@ -89,14 +89,14 @@ var constraints = []*constraint{
 	p1("dependentSchemas", constraintTODO, vfrom(VersionDraft2019_09)),
 	p2("deprecated", constraintDeprecated, vfrom(VersionDraft2019_09)|openAPI),
 	p2("description", constraintDescription, allVersions|openAPI),
-	p1("discriminator", constraintTODO, vset(VersionOpenAPI)),
+	p1("discriminator", constraintTODO, openAPI),
 	p1("else", constraintTODO, vfrom(VersionDraft7)),
 	p2("enum", constraintEnum, allVersions|openAPI),
-	p1("example", constraintTODO, vset(VersionOpenAPI)),
+	p1("example", constraintTODO, openAPI),
 	p2("examples", constraintExamples, vfrom(VersionDraft6)),
 	p2("exclusiveMaximum", constraintExclusiveMaximum, allVersions|openAPI),
 	p2("exclusiveMinimum", constraintExclusiveMinimum, allVersions|openAPI),
-	p1("externalDocs", constraintTODO, vset(VersionOpenAPI)),
+	p1("externalDocs", constraintTODO, openAPI),
 	p1("format", constraintTODO, allVersions|openAPI),
 	p1("id", constraintID, vto(VersionDraft4)),
 	p1("if", constraintTODO, vfrom(VersionDraft7)),
@@ -113,7 +113,7 @@ var constraints = []*constraint{
 	p3("minimum", constraintMinimum, allVersions|openAPI),
 	p2("multipleOf", constraintMultipleOf, allVersions|openAPI),
 	p3("not", constraintNot, allVersions|openAPI),
-	p2("nullable", constraintNullable, vset(VersionOpenAPI)),
+	p2("nullable", constraintNullable, openAPI),
 	p3("oneOf", constraintOneOf, allVersions|openAPI),
 	p2("pattern", constraintPattern, allVersions|openAPI),
 	p3("patternProperties", constraintPatternProperties, allVersions),
@@ -129,7 +129,7 @@ var constraints = []*constraint{
 	p1("unevaluatedProperties", constraintTODO, vfrom(VersionDraft2019_09)),
 	p2("uniqueItems", constraintUniqueItems, allVersions|openAPI),
 	p1("writeOnly", constraintTODO, vfrom(VersionDraft7)|openAPI),
-	p1("xml", constraintTODO, vset(VersionOpenAPI)),
+	p1("xml", constraintTODO, openAPI),
 }
 
 func p0(name string, f constraintFunc, versions versionSet) *constraint {