@Override
    public void checkValid(String literal, ValidationContext context) throws DatatypeException {
        checkValid(literal);
    }
Delegates to <code>checkValid(CharSequence literal)</code>.
@param literal the value
@param context the validation context (ignored by subclasses)
@throws DatatypeException if the literal does not conform to the datatype definition
@see org.relaxng.datatype.Datatype#checkValid(java.lang.String, org.relaxng.datatype.ValidationContext)
src/nu/validator/datatype/AbstractDatatype.java