simple-plugin-update-example.php

function simple_plugin_updater( $update_plugins, $transient_name ) {

	$plugin = json_decode(
		json_encode(
			array(
				'new_version' => 89,
				'stable_version' => 89,
				'name' => 'My Fake Plugin',
				'slug' => 'my-fake-plugin.php',
				'url' => 'https://myfakeplugin.com',
				'last_updated' => '2019-01-24 18:42:57',
				'homepage' => 'https://myfakeplugin.com',
				'package' => 'https://myfakeplugin.com/my-fake-plugin.zip',
				'download_link' => 'https://myfakeplugin.com',
				'sections' => array(
					'description' => wpautop( strip_tags( 'Description', '<p><li><ul><ol><strong><a><em>' ) ),
					'changelog'   => html_entity_decode( 'Changelog' )
				),
				'icons' => array(
					'2x' => 'https://philjdrums.com/wp-content/uploads/2019/01/Phil-J-Drums-1.png',
					'1x' => 'https://philjdrums.com/wp-content/uploads/2019/01/Phil-J-Drums-1.png',
					'svg' => 'https://philjdrums.com/wp-content/uploads/2019/01/Phil-J-Drums-1.png'
				),
				'banners' => array(
					'2x' => 'https://philjdrums.com/wp-content/uploads/2019/01/Phil-J-Drums-1.png',
					'1x' => 'https://philjdrums.com/wp-content/uploads/2019/01/Phil-J-Drums-1.png'
				),
				'description' => array(),
				'changelog' => array(),
				'tested' => 5.0
			)
		), false, 3
	);

	$plugin->sections = (array)$plugin->sections;
	$plugin->icons = (array)$plugin->icons;
	$plugin->banners = (array)$plugin->banners;
	$plugin->description = (array)$plugin->description;
	$plugin->changelog = (array)$plugin->changelog;
  	$plugin->plugin = 'my-fake-plugin/my-fake-plugin.php';

	$update_plugins->response['my-fake-plugin/my-fake-plugin.php'] = $plugin;

	return $update_plugins;

}
add_filter( 'pre_set_site_transient_update_plugins', 'simple_plugin_updater', 10, 2 );