@SuppressWarnings("unchecked") // returns default for both F and T
      T defaultConverter = (T) defaultConverter(convertFromType, convertToType);
      return defaultConverter;
    }
    if (type.getRawType().isInterface()) {
      return newDefaultReturningProxy(type);
    }
    return null;
  }

  private <F, T> Converter<F, T> defaultConverter(
      final TypeToken<F> convertFromType, final TypeToken<T> convertToType) {

      @SuppressWarnings("unchecked") // returns default for both F and T
      T defaultConverter = (T) defaultConverter(convertFromType, convertToType);
      return defaultConverter;
    }
    if (type.getRawType().isInterface()) {
      return newDefaultReturningProxy(type);
    }
    return null;
  }

  private <F, T> Converter<F, T> defaultConverter(
      final TypeToken<F> convertFromType, final TypeToken<T> convertToType) {

pkg database/sql/driver, type Valuer interface { Value }
pkg database/sql/driver, type Valuer interface, Value() (Value, error)
pkg database/sql/driver, var Bool boolType
pkg database/sql/driver, var DefaultParameterConverter defaultConverter
pkg database/sql/driver, var ErrBadConn error
pkg database/sql/driver, var ErrSkip error
pkg database/sql/driver, var Int32 int32Type
pkg database/sql/driver, var ResultNoRows noRows