improve openapi support

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

openapiv3_util.go

@@ -0,0 +1,39 @@
+package main
+
+import v3 "go.unistack.org/micro-proto/v3/openapiv3"
+
+func getMediaType(eopt interface{}) string {
+	ctype := "application/json"
+
+	if eopt == nil {
+		return ctype
+	}
+
+	if eopt == v3.E_Openapiv3Operation.InterfaceOf(v3.E_Openapiv3Operation.Zero()) {
+		return ctype
+	}
+
+	opt, ok := eopt.(*v3.Operation)
+	if !ok || opt.RequestBody == nil {
+		return ctype
+	}
+
+	if opt.GetRequestBody() == nil {
+		return ctype
+	}
+
+	if opt.GetRequestBody().GetRequestBody() == nil {
+		return ctype
+	}
+
+	c := opt.GetRequestBody().GetRequestBody().GetContent()
+	if c == nil {
+		return ctype
+	}
+
+	for _, prop := range c.GetAdditionalProperties() {
+		ctype = prop.Name
+	}
+
+	return ctype
+}