/** @param container must not be null. */
 public static IonWriter makeSystemWriter(IonContainer container) {
   IonSystem sys = container.getSystem();
   IonCatalog cat = sys.getCatalog();
   SymbolTable defaultSystemSymtab = sys.getSystemSymbolTable();
   IonWriter writer =
       new IonWriterSystemTree(defaultSystemSymtab, cat, container, null /* initialIvmHandling */);
   return writer;
 }
  /** @param container must not be null. */
  public static IonWriter makeWriter(IonCatalog catalog, IonContainer container) {
    IonSystem sys = container.getSystem();
    SymbolTable defaultSystemSymtab = sys.getSystemSymbolTable();

    // TODO the SUPPRESS here is a nasty discontinuity with other places
    // that create this kind of reader.  It prevents the Lite DG system
    // iterator from returning two IVMs at the start of the data.
    // The Span tests detect that problem.
    IonWriterSystemTree system_writer =
        new IonWriterSystemTree(
            defaultSystemSymtab, catalog, container, InitialIvmHandling.SUPPRESS);

    return new IonWriterUser(catalog, sys, system_writer);
  }