if there is no leave the header empty.

lib/rest_client.js

@@ -19,14 +19,24 @@ module.exports.RestClient = function (options) {
     public: options.accessToken,
     secret: options.accessTokenSecret
   };
+  function buildHeader(request_data, request_token = '')  {
+    if (request_token) {
+      return  { 'Authorization': 'Bearer ' + request_token };
+    }
+    if (oauth.consumer.public && oauth.consumer.secret) {
+      return oauth.toHeader(oauth.authorize(request_data, token))
+    }
+
+    return {};
+  }
 
   function apiCall(request_data, request_token = '') {
     logger.debug('Calling API endpoint: ' + request_data.method + ' ' + request_data.url + ' token: ' + request_token);
 
     logger.info({
       url: request_data.url,
       method: request_data.method,
-      headers: request_token ? { 'Authorization': 'Bearer ' + request_token } : oauth.toHeader(oauth.authorize(request_data, token)),
+      headers: buildHeader(request_token),
       json: true,
       body: request_data.body,
     });
@@ -35,7 +45,7 @@ module.exports.RestClient = function (options) {
       request({
         url: request_data.url,
         method: request_data.method,
-        headers: request_token ? { 'Authorization': 'Bearer ' + request_token } : oauth.toHeader(oauth.authorize(request_data, token)),
+        headers: buildHeader(request_token),
         json: true,
         body: request_data.body,
       }, function (error, response, body) {