```ruby
require File.expand_path('../boot', __FILE__)

require 'rails'
# Pick the frameworks you want:
require 'active_model/railtie'
require 'active_job/railtie'
require 'active_record/railtie'
require 'action_controller/railtie'
require 'action_mailer/railtie'
require 'action_view/railtie'
require 'rails/test_unit/railtie'

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module Hummingbird
  class Application < Rails::Application
    # Settings in config/environments/* take precedence over those specified
    # here.  Application configuration should go into files in
    # config/initializers -- all .rb files in that directory are automatically
    # loaded.

    # UTC all the way
    config.time_zone = 'UTC'

    # Do not swallow errors in after_commit/after_rollback callbacks.
    config.active_record.raise_in_transactional_callbacks = true

    # Include all concern directories in app/*/concerns
    concern_dirs = Dir['app/*/concerns'].map { |d| File.expand_path(d) }
    Rails.application.config.eager_load_paths += concern_dirs
    Rails.application.config.eager_load_paths.uniq!

    # We run under /api
    config.relative_url_root = '/api'
  end
end
```

Enable eager loading for lib/data_import directory
user
```ruby
require File.expand_path('../boot', __FILE__)

require 'rails'
# Pick the frameworks you want:
require 'active_model/railtie'
require 'active_job/railtie'
require 'active_record/railtie'
require 'action_controller/railtie'
require 'action_mailer/railtie'
require 'action_view/railtie'
require 'rails/test_unit/railtie'

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module Hummingbird
  class Application < Rails::Application
    # Settings in config/environments/* take precedence over those specified
    # here.  Application configuration should go into files in
    # config/initializers -- all .rb files in that directory are automatically
    # loaded.

    # UTC all the way
    config.time_zone = 'UTC'

    # Do not swallow errors in after_commit/after_rollback callbacks.
    config.active_record.raise_in_transactional_callbacks = true

    # Include all concern directories in app/*/concerns
    concern_dirs = Dir['app/*/concerns'].map { |d| File.expand_path(d) }
    config.eager_load_paths += concern_dirs
    # Include data_import and list_import
    config.eager_load_paths += %w[lib/data_import]
    # Rip out any non-uniqu entries
    config.eager_load_paths.uniq!

    # We run under /api
    config.relative_url_root = '/api'
  end
end
```
assistant