The string representation of value, or string.Empty if value is null.
To convert value to its string representation, the method tries to call the IConvertible.ToString(IFormatProvider) implementation of value. If value does not implement the IConvertible interface, the method tries to call the IFormattable.ToString(string, IFormatProvider) implementation of value. If value does not implement the IFormattable interface, the method calls the ToString method of the underlying type of value.