anchor.diff:          %% LUMA API Key, must be identical with API Key in external LUMA
           %% service.
           lumaApiKey => {string, optional},
  +        %% The type of storage.
  +        type => {equal, <<"nulldevice">>},
           %% Minimum latency in milliseconds, which should be simulated for
           %% selected operations.
           latencyMin => {integer, optional},
  
positive.code:         insecure => {boolean, optional},
          %% Defines whether storage is readonly.
          readonly => {boolean, optional},
          %% The type of storage.
          type => {equal, <<"webdav">>},
          %% If true LUMA and reverse LUMA services will be enabled.
          lumaEnabled => {boolean, optional},
          %% URL of external LUMA service
  
negative.code:         insecure => {boolean, optional},
          %% Defines whether storage is readonly.
          readonly => {boolean, optional},
          %% If true LUMA and reverse LUMA services will be enabled.
          lumaEnabled => {boolean, optional},
          %% URL of external LUMA service
  