protected function getAvatarUrl( $id, $size ) {
		$attachments_fallback_chain = $this->getAttachmentFallbackChain( $id );

		foreach ( $attachments_fallback_chain as $attachment_id ) {
			$image = wp_get_attachment_image_src( $attachment_id, $size );
			if ( ! empty( $image ) ) {
				return $image[0];
			}
		}

		return null;
	}