@Override
  default @NotNull Map<@NotNull DerivedVariableDescriptor, @NotNull DfType> getDerivedValues() {
    SpecialField field = getSpecialField();
    return field == null ? Map.of() : Map.of(field, getSpecialFieldType());
  }
@Override
  default @NotNull Map<@NotNull DerivedVariableDescriptor, @NotNull DfType> getDerivedValues()