Return an Empty Array in REST API Response

I know this is well beyond the scope of GeneratePress, but hoped the community might have some insights that could help me solve an issue I'm having with a REST API reply and a custom field.

In short I've created a custom REST API endpoint that serves data from a custom post type with ACF fields to a desktop application. The endpoint is working nicely except for one field when it has a blank value.

Specifically, the 'HostSoftwareSupportedVersions' field returns an array whenever one or more options are selected (what I need). Conversely, an empty string is returned whenever no options are selected. Although most items have a value, an empty value is acceptable in this case.

With that in mind, what I need is for WordPress to return an empty array, not string, if no option is selected. Below is the basic code I am working with. Again, the field I'm having trouble with is 'HostSoftwareSupportedVersions'

function dg_get_tools() {

  $args = array (

    'post_type' => 'tools',

    'post_status' => 'publish',

	'posts_per_page' => -1,

	);

 

  $items = array();

 

  if ( $posts = get_posts( $args ) ) {

    foreach ( $posts as $post ) {

      $items[] = array(

        'id' => $post->ID,

		'ContentType' => implode(wp_get_post_terms( $post->ID, 'itemtype', array( 'fields' => 'ids' ) )),

		'Name' => 'TEST ' .$post->post_title,

		'LongDescription' => $post->post_excerpt,

		'HostSoftware' => reset(get_post_meta($post->ID, 'software')),

		'HostSoftwareSupportedVersions' => reset(get_post_meta($post->ID, 'software-version')),

		'Url' =>  implode(get_post_meta($post->ID, 'item_url')),

      );

    }

  }

  return $items;

}