presto-main/src/main/java/io/prestosql/metadata/StaticCatalogStore.java/StaticCatalogStore/listFiles
class StaticCatalogStore:    private static List<File> listFiles(File installedPluginsDir)
    {
        if (installedPluginsDir != null && installedPluginsDir.isDirectory()) {
            File[] files = installedPluginsDir.listFiles();
            if (files != null) {
                return ImmutableList.copyOf(files);
            }
        }
        return ImmutableList.of();
    }