def validate_param(opts, key, required, default_val = nil)
      if required
        raise EwsBadArgumentError, "Required parameter(#{key}) not passed." unless opts.has_key?(key)
        opts[key]
      else
        raise EwsBadArgumentError, "Default value not supplied." unless default_val
        opts.has_key?(key) ? opts[key] : default_val
      end
    end
def validate_param(opts, key, required, default_val = nil)
      if required
        raise EwsBadArgumentError, "Required parameter(#{key}) not passed." unless opts.has_key?(key)
        opts[key]
      else
        raise EwsBadArgumentError, "Default value not supplied." unless default_val
        opts.has_key?(key) ? opts[key] : default_val
      end
    end
Private Methods (Builders and Parsers)
 Validate or set default values for options parameters.
 @param [Hash] opts The options parameter passed to an EWS operation
 @param [Symbol] key The key in the Hash we are validating
 @param [Boolean] required Whether or not this key is required
 @param [Object] default_val If the key is not required use this as a
   default value for the operation.