Getting below exception while calling a REST API using GROOVY script from Application Composer

groovy.lang.missingpropertyexception : no such property: result for class: java.lang.string

Code Snippet:

def ModeSelection = 

[

 ModeSelection :SelectMode_c,

]

def response;

response = adf.webServices.DeliveryPreferenceAPI.POST(ModeSelection)

setAttribute('Result_c',response.Result)