/usr/share/netbeans/platform13/modules/ext/ is in libnb-platform13-java 7.0.1+dfsg1-4.
This file is owned by root:root, with mode 0o755.
..
/usr/share/netbeans/platform13/modules/ext/antlr-3.1.3.jar
/usr/share/netbeans/platform13/modules/ext/felix-2.0.3.jar
/usr/share/netbeans/platform13/modules/ext/felix-main-2.0.2.jar
/usr/share/netbeans/platform13/modules/ext/hamcrest-core.jar
/usr/share/netbeans/platform13/modules/ext/jhall-2.0_05.jar
/usr/share/netbeans/platform13/modules/ext/jna-3.2.7.jar
/usr/share/netbeans/platform13/modules/ext/junit-4.8.2.jar
/usr/share/netbeans/platform13/modules/ext/junit-4.8.2.jar.external
/usr/share/netbeans/platform13/modules/ext/nsProxyAutoConfig.js
/usr/share/netbeans/platform13/modules/ext/osgi.cmpn-4.2.jar
/usr/share/netbeans/platform13/modules/ext/osgi.core-4.2.jar
/usr/share/netbeans/platform13/modules/ext/platform-3.2.7.jar
/usr/share/netbeans/platform13/modules/ext/stringtemplate-3.2.jar
/usr/share/netbeans/platform13/modules/ext/swing-layout-1.0.4.jar
/usr/share/netbeans/platform13/modules/ext/updater.jar