Validates Parameters args for command specified by its name using defined schema.
        If validation schema is not defined than the methods returns no errors.
        It returns validation error if the command is not found.
        
        :param command: the name of the command for which the 'args' must be validated.

        :param args: the parameters (arguments) to validate.
        
        :return: an array of ValidationResults. If no command is found by the given
                 name, then the returned array of ValidationResults will contain a
                 single entry, whose type will be ValidationResultType.Error.

def validate(self, command, args):
        """
        Validates Parameters args for command specified by its name using defined schema.
        If validation schema is not defined than the methods returns no errors.
        It returns validation error if the command is not found.
        
        :param command: the name of the command for which the 'args' must be validated.

        :param args: the parameters (arguments) to validate.
        
        :return: an array of ValidationResults. If no command is found by the given
                 name, then the returned array of ValidationResults will contain a
                 single entry, whose type will be ValidationResultType.Error.
        """
        cref = self.find_command(command)
        if cref == None:
            results = []
            results.append( \
                ValidationResult(
                    None, ValidationResultType.Error,
                    "CMD_NOT_FOUND", 
                    "Requested command does not exist"
                )
            )
            return results

        return cref.validate(args)