You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: workflow_filters_validator.rb
    path of file: ./repos/open-build-service/src/api/app/validators
    
    the code of the file until where you have to start completion: class WorkflowFiltersValidator < ActiveModel::Validator
  SUPPORTED_FILTER_VALUES = %i[only ignore].freeze
  DOCUMENTATION_LINK
    
  def validate(record)
    @workflow = record
    @workflow_instructions = record.workflow_instructions

    validate_filters

    # We use the `:filter` or `:filters` key to have error messages which read better, so we check both.
    return unless @workflow.errors.include?(:filter) || @workflow.errors.include?(:filters)

    # Guide users by sharing a link whenever there's a validation error
    @workflow.errors.add(:base, "Documentation for filters: #{DOCUMENTATION_LINK}")
  end