fix(sample-gen): should return json literal example (#6827)

* fix(sample-gen): should return json literal example

* test(sample-gen): should return json literal example

src/core/plugins/samples/fn.js

@@ -203,7 +203,17 @@ export const sampleFromSchemaGeneric = (schema, config={}, exampleOverride = und
 
     // if json just return
     if(!respectXML) {
-      return sample
+      // return if sample does not need any parsing
+      if(typeof sample !== "string") {
+        return sample
+      }
+      // check if sample is parsable or just a plain string
+      try {
+        return JSON.parse(sample)
+      } catch(e) {
+        // sample is just plain string return it
+        return sample
+      }
     }
 
     // recover missing type