JAR Index has been disabled in this release. JAR Index was an optimization to postpone downloading of JAR files when loading applets or other classes over the network. JAR Index has many long standing issues and does not interact well with newer features (such as, Multi-Release JARs and modular JARs). If a JAR file contains an INDEX.LIST file, then its contents are ignored by the application class loader and by any URLClassLoader created by user code.

The system property, `jdk.net.URLClassPath.enableJarIndex`, can be used re-enable the feature if required. If set to an empty string or the value "true", then JAR Index will be re-enabled. This system property is temporary. A future release will remove the JAR Index feature and the system property.

The change does not impact the `jar -i` option. The `jar` tool continues to create an index when this option is used.