PayPal.SOAP.MerchantAPICallPreHandler.GetHeaderMap C# (CSharp) Method

        public Dictionary<string, string> GetHeaderMap()
        {
            try
            {
                if (headers == null)
                {
                    headers = apiCallHandler.GetHeaderMap();
                    if (credential is SignatureCredential)
                    {
                        SignatureHttpHeaderAuthStrategy signatureHttpHeaderAuthStrategy = new SignatureHttpHeaderAuthStrategy(GetEndpoint());
                        headers = signatureHttpHeaderAuthStrategy.GenerateHeaderStrategy((SignatureCredential)credential);
                    }
                    else if (credential is CertificateCredential)
                    {
                        CertificateHttpHeaderAuthStrategy certificateHttpHeaderAuthStrategy = new CertificateHttpHeaderAuthStrategy(GetEndpoint());
                        headers = certificateHttpHeaderAuthStrategy.GenerateHeaderStrategy((CertificateCredential)credential);
                    }

                    foreach (KeyValuePair<string, string> pair in GetDefaultHttpHeadersSOAP())
                    {
                        headers.Add(pair.Key, pair.Value);
                    }
                }
            }
            catch (OAuthException oex)
            {
                throw oex;
            }
            return headers;
        }

 public void GetHeaderMapSignature()
 {
     credential = credentialMngr.GetCredentials(UnitTestConstants.APIUserName);
     soapHandler = new MerchantAPICallPreHandler(defaultSoapHandler, credential);
     Dictionary<String, String> headers = soapHandler.GetHeaderMap();
     Assert.IsNotNull(headers);
     Assert.IsTrue(headers.Count > 0);
     Assert.AreEqual(UnitTestConstants.APIUserName, headers[BaseConstants.PAYPAL_SECURITY_USERID_HEADER]);
     Assert.AreEqual(UnitTestConstants.APIPassword, headers[BaseConstants.PAYPAL_SECURITY_PASSWORD_HEADER]);
     Assert.AreEqual(UnitTestConstants.APISignature, headers[BaseConstants.PAYPAL_SECURITY_SIGNATURE_HEADER]);
     Assert.AreEqual(BaseConstants.SOAP, headers[BaseConstants.PAYPAL_REQUEST_DATA_FORMAT_HEADER]);
     Assert.AreEqual(BaseConstants.SOAP, headers[BaseConstants.PAYPAL_RESPONSE_DATA_FORMAT_HEADER]);
 }