feature: read the x-example field and use them as values (#3538)

* Read the x-example field and use them as values
Allow to show the value defined in the "x-example" field when pressing try-out. The "default" value will have the precedence over the x-example

* Use `parameterWithMeta` to get parameter data in <ParameterRow>
* Prefer specPath when fetching resolved subtrees in OperationContainer
* Add test for OAS3 callback rendering
* Remove debugger statement
* Pass base resolution URL directly to Swagger-Client subtree resolver
* Remove accidental comment
* Migrate additional options
* Don't default to empty Map when getting subtree
* make "default" and "x-example" mutually exclusive
"x-example" wins when both are present
* limit "x-example" to non-body parameters

src/core/components/parameter-row.jsx

@@ -24,11 +24,18 @@ export default class ParameterRow extends Component {
 
     let { specSelectors, pathMethod, param } = props
     let defaultValue = param.get("default")
+    let xExampleValue = param.get("x-example")
     let parameter = specSelectors.parameterWithMeta(pathMethod, param.get("name"), param.get("in"))
     let value = parameter ? parameter.get("value") : ""
-    if ( defaultValue !== undefined && value === undefined ) {
-      this.onChangeWrapper(defaultValue)
+
+    if( param.get("in") !== "body" ) {
+      if ( xExampleValue !== undefined && value === undefined ) {
+        this.onChangeWrapper(xExampleValue)
+      } else if ( defaultValue !== undefined && value === undefined ) {
+        this.onChangeWrapper(defaultValue)
+      }
     }
+
   }
 
   componentWillReceiveProps(props) {