SwiftLint/Source/SwiftLintFramework/Rules/RuleConfigurations/MultilineParametersConfiguration.swift

struct MultilineParametersConfiguration: SeverityBasedRuleConfiguration, Equatable {
    private(set) var severityConfiguration = SeverityConfiguration(.warning)
    private(set) var allowsSingleLine = true

    var consoleDescription: String {
        "severity: \(severityConfiguration.consoleDescription)"
            + ", allowsSingleLine: \(allowsSingleLine)"
    }

    mutating func apply(configuration: Any) throws {
        guard let configuration = configuration as? [String: Any] else {
            throw ConfigurationError.unknownConfiguration
        }

        allowsSingleLine = configuration["allows_single_line"] as? Bool ?? true

        if let severityString = configuration["severity"] as? String {
            try severityConfiguration.apply(configuration: severityString)
        }
    }
}