Data Source Error Web Contents failed to fetch data from web api(AWS AppSync Graphql API)

Hi,
I am trying to fetch data from AWS AppSync Graphql API in power BI . Providing these in headers [Headers=[#"Content-Type"="application/json", #"x-api-key"="xyz"]]

let
    qContent = "
    {
         query MyQuery {
                get_id{
                    id
                 }
            }
    }",
    cContent = Text.Replace(qContent, Character.FromNumber(34), Character.FromNumber(92) &  Character.FromNumber(34)),
    pContent = "{ ""query"": "& Character.FromNumber(34) & cContent & Character.FromNumber(34) & " }",
    bContent = Text.ToBinary(pContent),
    Source = Json.Document(Web.Contents("https://qeenqrsrivdvfnodt4w2ptgt3y.appsync-api.us-east-1.amazonaws.com/graphql", [Headers=[#"Content-Type"="application/json", #"x-api-key"="xyz"],Content=bContent])),
    data = Source[data],
    get_id = data[get_id],
    #"Converted to Table" = Table.FromList(get_id, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
    #"Expanded Column1" = Table.ExpandRecordColumn(#"Converted to Table", "Column1", {"id"}, {"id"})
in
    #"Expanded Column1"
The same api url and api key works in Postman but in power bi , I get 
DataSource.Error: Web.Contents failed to get contents from 'https://qeenqrsrivdvfnodt4w2ptgt3y.appsync-api.us-east-1.amazonaws.com/graphql' (400):
I am using Anonymous Type for credentials.
Does anyone has any idea about this issue?