code: @Nullable
    private StringBuilder getQualifiedNameForGetProp(int reserve) {
      String propName = getLastChild().getString();
      reserve += 1 + propName.length();  // +1 for the '.'
      StringBuilder builder;
      if (first.isGetProp()) {
        builder = first.getQualifiedNameForGetProp(reserve);
        if (builder == null) {
          return null;
        }
      } else {
        String left = first.getQualifiedName();
        if (left == null) {
          return null;
        }
        builder = new StringBuilder(left.length() + reserve);
        builder.append(left);
      }
      builder.append('.').append(propName);
      return builder;
    }
docs: Helper method for {@link #getQualifiedName} to handle GETPROP nodes.
  
  @param reserve The number of characters of space to reserve in the StringBuilder
  @return {@code null} if this is not a qualified name or a StringBuilder if it is a complex
  qualified name.