https://access.redhat.com/webassets/avalon/d/red_hat_jboss_enterprise_application_platform/8.1/javadocs/org/hibernate/search/backend/lucene/lowlevel/directory/spi/DirectoryHolder.html
DirectoryHolder (Red Hat JBoss Enterprise Application Platform 8.1.1.GA + JBoss EAP XP 6.0.0.GA...
declaration: package: org.hibernate.search.backend.lucene.lowlevel.directory.spi, interface: DirectoryHolder