List Subscribers: Add Support for include parameter

src/ConvertKit_API_Traits.php

@@ -1170,6 +1170,7 @@ public function get_post(int $id)
      * @param \DateTime|null $updated_before      Filter subscribers who have been updated before this date.
      * @param string         $sort_field          Sort Field (id|updated_at|cancelled_at).
      * @param string         $sort_order          Sort Order (asc|desc).
+     * @param array<string>  $include             Additional fields to include: attribution, tags, location, canceled_at.
      * @param boolean        $include_total_count To include the total count of records in the response, use true.
      * @param string         $after_cursor        Return results after the given pagination cursor.
      * @param string         $before_cursor       Return results before the given pagination cursor.
@@ -1190,6 +1191,7 @@ public function get_subscribers(
         \DateTime|null $updated_before = null,
         string $sort_field = 'id',
         string $sort_order = 'desc',
+        array $include = [],
         bool $include_total_count = false,
         string $after_cursor = '',
         string $before_cursor = '',
@@ -1222,6 +1224,9 @@ public function get_subscribers(
         if (!empty($sort_order)) {
             $options['sort_order'] = $sort_order;
         }
+        if (!empty($include)) {
+            $options['include'] = implode(',', $include);
+        }
 
         // Send request.
         return $this->get(

tests/ConvertKitAPITest.php

@@ -3721,6 +3721,28 @@ public function testGetSubscribersWithSortOrderParam()
         );
     }
 
+    /**
+     * Test that get_subscribers() returns the expected data
+     * when the include parameter is used.
+     *
+     * @since   2.5.0
+     *
+     * @return void
+     */
+    public function testGetSubscribersWithIncludeParam()
+    {
+        $result = $this->api->get_subscribers(
+            include: ['tags']
+        );
+
+        // Assert subscribers and pagination exist.
+        $this->assertDataExists($result, 'subscribers');
+        $this->assertPaginationExists($result);
+
+        // Assert fields are included.
+        $this->assertArrayHasKey('tags', get_object_vars($result->subscribers[0]));
+    }
+
     /**
      * Test that get_subscribers() returns the expected data
      * when pagination parameters and per_page limits are specified.