Refine json for method getlinknodes

main.py

@@ -148,8 +148,8 @@ async def fastapi_get_link_nodes(network: str, link: str):
     return JSONResponse(
         status_code = status.HTTP_200_OK,
         content={
-            'start': result.value.from_node,
+            'start': str(result.value.from_node, 'utf-8'),
-            'end': result.value.to_node 
+            'end': str(result.value.to_node, 'utf-8')
         })
 
 @app.post("/addlink/")