in src/DocBlock/DocBlock.hack [233:242]
protected static function typeToTypes(?string $type): vec<string> {
if ($type === null) {
return vec[];
}
return $type
|> Str\strip_prefix($$, '[')
|> Str\strip_suffix($$, ']')
|> Str\split($$, '|')
|> Vec\map($$, $x ==> Str\trim($x));
}