Summary

Document the JDK-specific JAR file attributes Add-Exports, Add-Opens and Enable-Native-Access in the JAR file specification. These attributes are supported in the main section of the JAR manifest for stand-alone applications deployed as executable JAR files.

Problem

JEP 261 ("Module System") defined the JDK-specific JAR-file manifest attributes "Add-Exports" and "Add-Opens" to allow code in the executable JAR file access JDK internals without needing the --add-exports and --add-opens command line options.

JEP 454 ("Foreign Function & Memory API") defined the JDK-specific JAR-file manifest attribute "Enable-Native-Access" to allow code in the executable JAR call restricted methods without needing to use the --enable-native-access command-line option.

The JAR file attributes are documented in the JEPs but are not documented in the JAR file spec.

Solution

Document the "Add-Exports", "Add-Opens", and "Enable-Native-Access" JAR manifest attributes in the JAR File Specification.

Specification

+++ b/closed/src/java.base/share/specs/jar/jar.md
@@ -344,6 +344,30 @@ of the manifest. They fall into the following different groups:
         JAR file are defaulted to be sealed, unless they are defined
         otherwise individually.  See also the [Package Sealing](#package-sealing) section.

+In addition to the above Main attributes defined by the Java Platform, the JDK
+Reference Implementation also supports the following attributes for stand-alone
+applications that are bundled into executable JAR files. These attributes are
+ignored for JAR files that are not run with "`java -jar x.jar`".
+
+-   Add-Exports: Updates modules to export packages to all unnamed modules. The
+    value is a space-separated list of `<module>/<package>` pairs, where
+    `<module>` is a module name and `<package>` is a package in that module. It
+    is equivalent to running with `--add-exports <module>/<package>=ALL-UNNAMED`
+    for each `<module>/<package>` pair in the list. If a pair's `<module>` is
+    not resolved, or doesn't contain the indicated `<package>`, the
+    corresponding pair is ignored.
+-   Add-Opens: Updates modules to open packages to all unnamed modules. The
+    value is a space-separated list of `<module>/<package>` pairs, where
+    `<module>` is a module name and `<package>` is a package in that module. It
+    is equivalent to running with `--add-opens <module>/<package>=ALL-UNNAMED`
+    for each `<module>/<package>` pair in the list. If a pair's `<module>` is
+    not resolved, or doesn't contain the indicated `<package>`, the
+    corresponding pair is ignored.
+-   Enable-Native-Access: Enables native access for all code on the classpath
+    (including the code in the executable JAR itself). The only supported value
+    is `ALL-UNNAMED`; no other module name can be given. It is equivalent to
+    running with `--enable-native-access ALL-UNNAMED`.
+
 ### Per-Entry Attributes