code: function _gpfBuildMimeTypeFromMappings (path, mappings) {
      _gpfObjectForEach(mappings, function (extensions, key) {
          var mimeType = path + key;
          if (0 === extensions) {
              _createMimeTypeExtensionMapping(mimeType, "." + key);
  
          } else if ("string" === typeof extensions) {
              extensions.split(",").forEach(function (extension) {
                  _createMimeTypeExtensionMapping(mimeType, "." + extension);
              });
  
          } else { // Assuming extensions is an object
              _gpfBuildMimeTypeFromMappings(mimeType + "/", extensions);
          }
      });
  }
docs: Recursive function that fills _gpfMimeTypesToExtension & _gpfMimeTypesFromExtension
  
  @param {String} path
  @param {Object} mappings
  @private