Update a domain parameter.

The unique key used to identify the parameter.

The new value to apply for the parameter. Skip this if no update should be made.

The parameter's description. Skip this if no update should be made or set with an empty string to delete the current value.

Whether the parameter should be exposed to test sessions. Skip this if no update should be made.

The API key identifying the domain of the parameter. This is required if the community API key used for authentication refers to a community that is not linked to a specific domain.