protoc-gen-{grpc-gateway,openapiv2}: add optional support

Let `protoc` know that these generators support optional keywords. This
is by no means an implementation in `grpc-gateway` of the optional aware
generated code, it's just shielding of being considered as blockers in
code generation workflows.

Closes #1278

examples/internal/clients/abe/api/swagger.yaml

@@ -403,6 +403,13 @@ paths:
         type: "string"
         x-exportParamName: "OutputOnlyStringViaFieldBehaviorAnnotation"
         x-optionalDataType: "String"
+      - name: "optionalStringValue"
+        in: "query"
+        description: "mark a field as optional."
+        required: false
+        type: "string"
+        x-exportParamName: "OptionalStringValue"
+        x-optionalDataType: "String"
       responses:
         200:
           description: "A successful response."
@@ -714,6 +721,13 @@ paths:
         type: "string"
         x-exportParamName: "OutputOnlyStringViaFieldBehaviorAnnotation"
         x-optionalDataType: "String"
+      - name: "optionalStringValue"
+        in: "query"
+        description: "mark a field as optional."
+        required: false
+        type: "string"
+        x-exportParamName: "OptionalStringValue"
+        x-optionalDataType: "String"
       responses:
         200:
           description: "A successful response."
@@ -1012,6 +1026,13 @@ paths:
         type: "string"
         x-exportParamName: "OutputOnlyStringViaFieldBehaviorAnnotation"
         x-optionalDataType: "String"
+      - name: "optionalStringValue"
+        in: "query"
+        description: "mark a field as optional."
+        required: false
+        type: "string"
+        x-exportParamName: "OptionalStringValue"
+        x-optionalDataType: "String"
       responses:
         200:
           description: "A successful response."
@@ -1330,6 +1351,13 @@ paths:
         type: "string"
         x-exportParamName: "OutputOnlyStringViaFieldBehaviorAnnotation"
         x-optionalDataType: "String"
+      - name: "optionalStringValue"
+        in: "query"
+        description: "mark a field as optional."
+        required: false
+        type: "string"
+        x-exportParamName: "OptionalStringValue"
+        x-optionalDataType: "String"
       responses:
         200:
           description: "A successful response."
@@ -2698,6 +2726,9 @@ definitions:
         type: "string"
         title: "mark a field as readonly in Open API definition"
         readOnly: true
+      optionalStringValue:
+        type: "string"
+        title: "mark a field as optional"
     externalDocs:
       description: "Find out more about ABitOfEverything"
       url: "https://github.com/grpc-ecosystem/grpc-gateway"

examples/internal/clients/abe/api_a_bit_of_everything_service.go

@@ -222,6 +222,7 @@ ABitOfEverythingServiceApiService
      * @param "NestedAnnotationOk" (optional.String) -  DeepEnum description.   - FALSE: FALSE is false.  - TRUE: TRUE is true.
      * @param "Int64OverrideType" (optional.Int64) - 
      * @param "OutputOnlyStringViaFieldBehaviorAnnotation" (optional.String) -  mark a field as readonly in Open API definition.
+     * @param "OptionalStringValue" (optional.String) -  mark a field as optional.
 
 @return ExamplepbABitOfEverything
 */
@@ -259,6 +260,7 @@ type ABitOfEverythingServiceCheckGetQueryParamsOpts struct {
 	NestedAnnotationOk optional.String
 	Int64OverrideType optional.Int64
 	OutputOnlyStringViaFieldBehaviorAnnotation optional.String
+	OptionalStringValue optional.String
 }
 
 func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceCheckGetQueryParams(ctx context.Context, singleNestedName string, floatValue float32, requiredStringViaFieldBehaviorAnnotation string, localVarOptionals *ABitOfEverythingServiceCheckGetQueryParamsOpts) (ExamplepbABitOfEverything, *http.Response, error) {
@@ -376,6 +378,9 @@ func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceCheckGetQuery
 	if localVarOptionals != nil && localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.IsSet() {
 		localVarQueryParams.Add("outputOnlyStringViaFieldBehaviorAnnotation", parameterToString(localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.Value(), ""))
 	}
+	if localVarOptionals != nil && localVarOptionals.OptionalStringValue.IsSet() {
+		localVarQueryParams.Add("optionalStringValue", parameterToString(localVarOptionals.OptionalStringValue.Value(), ""))
+	}
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{"application/json", "application/x-foo-mime"}
 
@@ -547,6 +552,7 @@ ABitOfEverythingServiceApiService
      * @param "NestedAnnotationAmount" (optional.Int64) - 
      * @param "Int64OverrideType" (optional.Int64) - 
      * @param "OutputOnlyStringViaFieldBehaviorAnnotation" (optional.String) -  mark a field as readonly in Open API definition.
+     * @param "OptionalStringValue" (optional.String) -  mark a field as optional.
 
 @return ExamplepbABitOfEverything
 */
@@ -584,6 +590,7 @@ type ABitOfEverythingServiceCheckNestedEnumGetQueryParamsOpts struct {
 	NestedAnnotationAmount optional.Int64
 	Int64OverrideType optional.Int64
 	OutputOnlyStringViaFieldBehaviorAnnotation optional.String
+	OptionalStringValue optional.String
 }
 
 func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceCheckNestedEnumGetQueryParams(ctx context.Context, singleNestedOk string, floatValue float32, requiredStringViaFieldBehaviorAnnotation string, localVarOptionals *ABitOfEverythingServiceCheckNestedEnumGetQueryParamsOpts) (ExamplepbABitOfEverything, *http.Response, error) {
@@ -701,6 +708,9 @@ func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceCheckNestedEn
 	if localVarOptionals != nil && localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.IsSet() {
 		localVarQueryParams.Add("outputOnlyStringViaFieldBehaviorAnnotation", parameterToString(localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.Value(), ""))
 	}
+	if localVarOptionals != nil && localVarOptionals.OptionalStringValue.IsSet() {
+		localVarQueryParams.Add("optionalStringValue", parameterToString(localVarOptionals.OptionalStringValue.Value(), ""))
+	}
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{"application/json", "application/x-foo-mime"}
 
@@ -871,6 +881,7 @@ ABitOfEverythingServiceApiService
      * @param "NestedAnnotationOk" (optional.String) -  DeepEnum description.   - FALSE: FALSE is false.  - TRUE: TRUE is true.
      * @param "Int64OverrideType" (optional.Int64) - 
      * @param "OutputOnlyStringViaFieldBehaviorAnnotation" (optional.String) -  mark a field as readonly in Open API definition.
+     * @param "OptionalStringValue" (optional.String) -  mark a field as optional.
 
 @return ExamplepbABitOfEverything
 */
@@ -906,6 +917,7 @@ type ABitOfEverythingServiceCheckPostQueryParamsOpts struct {
 	NestedAnnotationOk optional.String
 	Int64OverrideType optional.Int64
 	OutputOnlyStringViaFieldBehaviorAnnotation optional.String
+	OptionalStringValue optional.String
 }
 
 func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceCheckPostQueryParams(ctx context.Context, stringValue string, body ABitOfEverythingNested, floatValue float32, requiredStringViaFieldBehaviorAnnotation string, localVarOptionals *ABitOfEverythingServiceCheckPostQueryParamsOpts) (ExamplepbABitOfEverything, *http.Response, error) {
@@ -1017,6 +1029,9 @@ func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceCheckPostQuer
 	if localVarOptionals != nil && localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.IsSet() {
 		localVarQueryParams.Add("outputOnlyStringViaFieldBehaviorAnnotation", parameterToString(localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.Value(), ""))
 	}
+	if localVarOptionals != nil && localVarOptionals.OptionalStringValue.IsSet() {
+		localVarQueryParams.Add("optionalStringValue", parameterToString(localVarOptionals.OptionalStringValue.Value(), ""))
+	}
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{"application/json", "application/x-foo-mime"}
 
@@ -2492,6 +2507,7 @@ ABitOfEverythingServiceApiService
      * @param "NestedAnnotationOk" (optional.String) -  DeepEnum description.   - FALSE: FALSE is false.  - TRUE: TRUE is true.
      * @param "Int64OverrideType" (optional.Int64) - 
      * @param "OutputOnlyStringViaFieldBehaviorAnnotation" (optional.String) -  mark a field as readonly in Open API definition.
+     * @param "OptionalStringValue" (optional.String) -  mark a field as optional.
 
 @return interface{}
 */
@@ -2530,6 +2546,7 @@ type ABitOfEverythingServiceGetQueryOpts struct {
 	NestedAnnotationOk optional.String
 	Int64OverrideType optional.Int64
 	OutputOnlyStringViaFieldBehaviorAnnotation optional.String
+	OptionalStringValue optional.String
 }
 
 func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceGetQuery(ctx context.Context, uuid string, floatValue float32, requiredStringViaFieldBehaviorAnnotation string, localVarOptionals *ABitOfEverythingServiceGetQueryOpts) (interface{}, *http.Response, error) {
@@ -2650,6 +2667,9 @@ func (a *ABitOfEverythingServiceApiService) ABitOfEverythingServiceGetQuery(ctx
 	if localVarOptionals != nil && localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.IsSet() {
 		localVarQueryParams.Add("outputOnlyStringViaFieldBehaviorAnnotation", parameterToString(localVarOptionals.OutputOnlyStringViaFieldBehaviorAnnotation.Value(), ""))
 	}
+	if localVarOptionals != nil && localVarOptionals.OptionalStringValue.IsSet() {
+		localVarQueryParams.Add("optionalStringValue", parameterToString(localVarOptionals.OptionalStringValue.Value(), ""))
+	}
 	// to determine the Content-Type header
 	localVarHttpContentTypes := []string{"application/json", "application/x-foo-mime"}
 

examples/internal/clients/abe/model_examplepb_a_bit_of_everything.go

@@ -60,4 +60,5 @@ type ExamplepbABitOfEverything struct {
 	Int64OverrideType int64 `json:"int64OverrideType,omitempty"`
 	RequiredStringViaFieldBehaviorAnnotation string `json:"requiredStringViaFieldBehaviorAnnotation"`
 	OutputOnlyStringViaFieldBehaviorAnnotation string `json:"outputOnlyStringViaFieldBehaviorAnnotation,omitempty"`
+	OptionalStringValue string `json:"optionalStringValue,omitempty"`
 }