The endorsed-standards override mechanism  allows implementations of newer versions of standards maintained outside of the Java Community Process, or of standalone APIs that are part of the Java SE Platform yet continue to evolve independently, to be installed into a run-time image.
A modular image is composed of modules rather than jar files. Going forward we expect to support endorsed standards and standalone APIs in modular form only, via the concept of upgradeable modules .
This feature will be deprecated in 8u40 and may be removed in a future JDK release . There is no change to the default behavior.