class Goliath::Rack::Validation::RequiredParam

def key_valid?(params)
  key_path = Array(@key)
  current_value = params
  # check that the full path is present
  # omit the last part of the path
  key_path[0...-1].each do |key_part|
    # if the key is missing or is nil the validation failed
    if !current_value.is_a?(Hash) || current_value[key_part].nil?
      return false
    end
    current_value = current_value[key_part]
  end
  # if we are here the full path is available, now test the real key
  val = current_value[key_path[-1]]
  case val
  when nil
    return false
  when String
    # if val is a string it must not be empty
    return false if val !~ NON_WHITESPACE_REGEXP
  when Array
    unless val.compact.empty?
       val.each do |k|
         return true unless k.is_a?(String)
         return true unless k !~ NON_WHITESPACE_REGEXP
       end
     end
    return false
  end
  true
end