curl "https://test.api.amadeus.com/v1/security/oauth2/token" \
     -H "Content-Type: application/x-www-form-urlencoded" \
     -d "grant_type=client_credentials&client_id={client_id}&client_secret={client_secret}"

curl "https://test.api.amadeus.com/v1/security/oauth2/token" -H "Content-Type: application/x-www-form-urlencoded" -d "grant_type=client_credentials&client_id=&client_secret="

C:\Users\sangbinlee9>curl "https://test.api.amadeus.com/v1/security/oauth2/token" -H "Content-Type: application/x-www-form-urlencoded" -d "grant_type=client_credentials&client_id=&client_secret="

        {
            "type": "amadeusOAuth2Token",
            "username": "sangbinlee9@gmail.com",
            "application_name": "flight booking app",
            "client_id": "",
            "token_type": "Bearer",
            "access_token": "",
            "expires_in": 1799,
            "state": "approved",
            "scope": ""
        }# air