Add default value for sortOrder in Plugins

[jlnarvaez]

Purpose of this pull request

This pull request (PR) add specification about the default value of sortOrder in Plugins declaration. (https://github.com/magento/magento2/blob/fcebd3a4ad2a6863af2e2092f5e548cbd81cb0f8/lib/internal/Magento/Framework/Interception/PluginList/PluginList.php#L160)

Affected pages

• https://developer.adobe.com/commerce/php/development/components/plugins/

Closes #234

[meker12]

Update validated against the code base:

I'll help you validate whether this default value for plugin sortOrder is correct. Let me search the Magento 2 repository to verify this information.Based on my search of the Magento 2 codebase, the default value for plugin sortOrder is indeed PHP_INT_MIN, and this is correct.

Evidence

The code confirms this in two key locations:

uasort($plugins, function ($itemA, $itemB) {
    return ($itemA['sortOrder'] ?? PHP_INT_MIN) - ($itemB['sortOrder'] ?? PHP_INT_MIN);
});

protected function _sort($itemA, $itemB)
{
    return ($itemA['sortOrder'] ?? PHP_INT_MIN) - ($itemB['sortOrder'] ?? PHP_INT_MIN);
}

What This Means

When a plugin's sortOrder is not explicitly defined, it defaults to PHP_INT_MIN (the smallest possible integer value). This ensures that plugins without a specified sort order run first in the execution chain, while plugins with higher sort order values run later. The sorting is done in ascending order, so lower values execute before higher values.