```ruby
module Discordrb::Webhooks
  # A class that acts as a builder for a webhook message object.
  class Builder
    def initialize(content: '', username: nil, avatar_url: nil, tts: false, file: nil, embeds: [])
      @content = content
      @username = username
      @avatar_url = avatar_url
      @tts = tts
      @file = file
      @embeds = embeds
    end

    # The content of the message. May be 2000 characters long at most.
    # @return [String] the content of the message.
    attr_accessor :content

    # The username the webhook will display as. If this is not set, the default username set in the webhook's settings
    # will be used instead.
    # @return [String] the username.
    attr_accessor :username
  end
end
```

Add an accessor for the avatar URL
user
```ruby
module Discordrb::Webhooks
  # A class that acts as a builder for a webhook message object.
  class Builder
    def initialize(content: '', username: nil, avatar_url: nil, tts: false, file: nil, embeds: [])
      @content = content
      @username = username
      @avatar_url = avatar_url
      @tts = tts
      @file = file
      @embeds = embeds
    end

    # The content of the message. May be 2000 characters long at most.
    # @return [String] the content of the message.
    attr_accessor :content

    # The username the webhook will display as. If this is not set, the default username set in the webhook's settings
    # will be used instead.
    # @return [String] the username.
    attr_accessor :username

    # The URL of an image file to be used as an avatar. If this is not set, the default avatar from the webhook's
    # settings will be used instead.
    # @return [String] the avatar URL.
    attr_accessor :avatar_url
  end
end
```
assistant