Summary

• Fixes namespace prefixing incorrectly applying to built-in PHP types like null
• Adds helper method maybe_prefix_namespace() to centralize namespace logic
• Includes test case to prevent regression

Problem

When a namespace was configured, built-in PHP types were being incorrectly prefixed. For example:

/**
 * @param null   $pre      The pre-existing value.
 * @param string $username The username.
 */
$pre = apply_filters( 'activitypub_pre_get_by_username', null, $username );

Would generate documentation showing ActivityPub\null instead of just null.

Solution

• Created maybe_prefix_namespace() helper method to handle all namespace prefixing logic in one place
• Expanded list of built-in types to exclude: null, mixed, void, false, true, callable, resource, iterable
• Applied fix to both parameter and return type handling

Test Plan

• Added test case test_null_param_without_namespace_prefix() with fixture
• Test fails before fix (shows ActivityPub\null)
• Test passes after fix (shows null)
• All 38 existing tests still pass