The flag to indicate whether this property is hidden from client applications.

If a property is not hidden, the property will come along with an access token. For example, if you set the properties request parameter as follows when you call Authlete /auth/token API,

[
    {
        "key":"example_parameter",
        "value":"example_value",
        "hidden":false
    }
]

The value of responseContent in the response from the API will contain the pair of example_parameter and example_value like below,

{
  ...
  "responseContent": "{\"access_token\":\"(abbrev)\",\"example_parameter\":\"example_value\",...}"
}

and this will result in that the client application will receive a JSON which contains the pair like the following.

{
  "access_token":"(abbrev)",
  "example_parameter":"example_value",
  ...
}

On the other hand, if you mark a property as hidden like below,

[
  {
    "key":"hidden_parameter",
    "value":"hidden_value",
    "hidden":true
  }
]

The client application will never see the property in any response from your authorization server. However, of course, the property is still associated with the access token and it can be confirmed by calling Authlete /auth/introspection API (which is an API to get information about an access token). A response from the API contains all properties associated with the given access token regardless of whether they are hidden or visible. The following is an example from Authlete introspection API.

{
  "type":"introspectionResponse",
  "resultCode":"A056001",
  "resultMessage":"[A056001] The access token is valid.",
  "action":"OK",
  "clientId":5008706718,
  "existent":true,
  "expiresAt":1463310477000,
  "properties":[
    {
      "hidden":false,
      "key":"example_parameter",
      "value":"example_value"
    },
    {
      "hidden":true,
      "key":"hidden_parameter",
      "value":"hidden_value"
    }
  ],
  "refreshable":true,
  "responseContent":"Bearer error=\"invalid_request\"",
  "subject":"user123",
  "sufficient":true,
  "usable":true
}

The key.

The value.