/// <summary>
/// Tries to find an <see cref="ExternalStreamWrapper"/> a given <paramref name="scheme"/>.
/// </summary>
/// <param name="scheme">The scheme portion of an URL.</param>
/// <returns>An <see cref="ExternalStreamWrapper"/> associated with the given <paramref name="scheme"/>
/// or <c>null</c> if the wrapper was not found.</returns>
public static ExternalStreamWrapper GetExternalWrapperByScheme(string scheme)
{
IExternalStreamWrapper proxy = Externals.GetStreamWrapper(scheme);
return(proxy == null ? null : new ExternalStreamWrapper(proxy, scheme));
}