That&#x27;s why it&#x27;s called a modular jar. There is also this &quot;jmod&quot; file described as:<p>&quot;For the purpose of modularizing the Java SE Platform’s reference implementation, the JDK, we will introduce a new artifact format that goes beyond JAR files to accommodate native code, configuration files, and other kinds of data that do not fit naturally, if at all, into JAR files. This format leverages another advantage of expressing module declarations in source files and compiling them into class files, namely that class files are independent of any particular artifact format. Whether this new format, provisionally named “JMOD,” should be standardized is an open question.&quot;<p>Edit: from <a href="http:&#x2F;&#x2F;mreinhold.org&#x2F;blog&#x2F;jigsaw-modular-images" rel="nofollow">http:&#x2F;&#x2F;mreinhold.org&#x2F;blog&#x2F;jigsaw-modular-images</a><p>&quot;The internal files rt.jar, tools.jar, and dt.jar have been removed. The content of these files is now stored in a more efficient format in implementation-private files in the lib directory.&quot;