Using composer 1.10:
Deprecation Notice: Class Elasticsearch\Endpoints\Ingest\Pipeline\ProcessorGrok located in ./elasticsearch/elasticsearch/src/Elasticsearch/Endpoints/Ingest/ProcessorGrok.php does not comply with psr-4 autoloading standard. It will not autoload anymore in Composer v2.0. in phar:///usr/local/Cellar/composer/1.10.0/bin/composer/src/Composer/Autoload/ClassMapGenerator.php:185