sclass DefaultValueConverterForField implements ValueConverterForField {
  public OrError<O> convertValue(O object, Field field, O value) {
    Class actualType = field.getType();
    Class type = primitiveToBoxedTypeOpt(actualType);

    // nothing to do
    
    if (isInstance(type, value))
      ret OrError(value);
    
    // int magic
    
    if (type == Int.class && !value instanceof Int)
      ret OrError(toInt(trimIfString(value));

    // double magic
    
    if (type == Double.class && !value instanceof Double)
      ret OrError(toDouble(trimIfString(value));

    // bool magic
    
    if (type == Bool.class && value instanceof S)
      if (actualType == Bool.class && eq(value, ""))
        ret OrError(null);
      else
        ret OrError(eqicOneOf((S) value, "1", "true", "yes"));

    // GlobalID magic
    
    ifclass GlobalID
    if (type == GlobalID.class && value instanceof S)
      ret OrError(GlobalID((S) value));
    endif
    
    ret OrError(value);
  }
}

Began life as a copy of #1026010