public sealed class VersionDescription 

public Version CreateVersion(Geodatabase geodatabase, string versionName, string description, VersionAccessType versionAccessType)
{
  if (!geodatabase.IsVersioningSupported()) return null;

  using (VersionManager versionManager = geodatabase.GetVersionManager())
  {
    VersionDescription versionDescription = new VersionDescription(versionName, description, versionAccessType);
    return versionManager.CreateVersion(versionDescription);
  }
}