private function parseNewAccessTokenFromResponse($body, $realmID = null){
        if(is_string($body)){
           $json_body = json_decode($body, true);
           if(json_last_error() === JSON_ERROR_NONE){
              $tokenExpiresTime = $json_body[CoreConstants::EXPIRES_IN];
              $refreshToken = $json_body[CoreConstants::OAUTH2_REFRESH_GRANTYPE];
              $refreshTokenExpiresTime = $json_body[CoreConstants::X_REFRESH_TOKEN_EXPIRES_IN];
              $accessToken = $json_body[CoreConstants::ACCESS_TOKEN];
              $this->checkIfEmptyValueReturned($tokenExpiresTime, $refreshToken, $refreshTokenExpiresTime, $accessToken);
              //If we have a response of OAuth 2 Access Token and the access token is not set, it must come from initial request. Create a dummy access token and update it.
              if(!isset($this->oauth2AccessToken)){
                  $this->oauth2AccessToken = new OAuth2AccessToken($this->getClientID(), $this->getClientSecret());
              }
              $this->oauth2AccessToken->updateAccessToken($tokenExpiresTime, $refreshToken, $refreshTokenExpiresTime, $accessToken);
              if(isset($realmID)){
                   $this->oauth2AccessToken->setRealmID($realmID);
              }
              return $this->oauth2AccessToken;
           }else{
              throw new SdkException("JSON DECODE encounters error:" . json_last_error());
           }
        }
    }