const CompressionOptions({bool clientNoContextTakeover: false, bool serverNoContextTakeover: false, int clientMaxWindowBits, int serverMaxWindowBits, bool enabled: true})

Source 

const CompressionOptions(
    {this.clientNoContextTakeover: false,
    this.serverNoContextTakeover: false,
    this.clientMaxWindowBits,
    this.serverMaxWindowBits,
    this.enabled: true});