Mentioned in [56128] on Core SVN:
HTTP API: Declare a few default parameters in `WP_Http_Curl` and `WP_Http_Streams`.

Created ticket #52622 on Core Trac:
Fix PHP Warning on PHP7.2 in class-wp-http-curl.php

Created ticket #49002 on Core Trac:
class-wp-hooks.php -> function apply_filters() -> Add source code: ...