How can I reference the Configuration from CustomDomainCommand Header button?

public class VaultApplication
        : MFiles.VAF.Extensions.ConfigurableVaultApplicationBase<Configuration>

    {


        public CustomDomainCommand cmdHeaderButtonCommand { get; }
        
        public VaultApplication()
        {
            this.cmdHeaderButtonCommand = new CustomDomainCommand
            {
                ID = "cmdHeaderButtonCommand",
                Execute = (c, o) =>
                {
                    string returntest = this.Configuration.MyStringValue;
                    o.ShowMessage(""+returntest);
                },
                DisplayName = "Test Contents",
                Locations = new List<ICommandLocation>
                {
                    new ButtonBarCommandLocation()
                }
            }
        };

        /// <inheritdoc />
        public override IEnumerable<CustomDomainCommand> GetCommands(IConfigurationRequestContext context)
        {
            return new List<CustomDomainCommand>(base.GetCommands(context))
            {
            this.cmdHeaderButtonCommand,
            };
        }

    }

public class VaultApplication 
: MFiles.VAF.Extensions.ConfigurableVaultApplicationBase<Configuration>
{

	[CustomCommand("Test Contents")]
	[ButtonBarCommandLocation]
	public void SayHello
	(
		IConfigurationRequestContext context, 
		ClientOperations operations
	)
	{
        string returntest = this.Configuration.MyStringValue;
        operations.ShowMessage(""+returntest);
	}
}