/usr/share/gradle/lib/plugins/ is in libgradle-plugins-java 1.4-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gradle/lib/plugins/CodeNarc.jar
/usr/share/gradle/lib/plugins/GMetrics.jar
/usr/share/gradle/lib/plugins/ant-antlr.jar
/usr/share/gradle/lib/plugins/antlr.jar
/usr/share/gradle/lib/plugins/bcpg.jar
/usr/share/gradle/lib/plugins/bcprov.jar
/usr/share/gradle/lib/plugins/bndlib.jar
/usr/share/gradle/lib/plugins/checkstyle.jar
/usr/share/gradle/lib/plugins/commons-cli.jar
/usr/share/gradle/lib/plugins/eclipse-ecj.jar
/usr/share/gradle/lib/plugins/gradle-announce-1.4.jar
/usr/share/gradle/lib/plugins/gradle-antlr-1.4.jar
/usr/share/gradle/lib/plugins/gradle-build-comparison-1.4.jar
/usr/share/gradle/lib/plugins/gradle-code-quality-1.4.jar
/usr/share/gradle/lib/plugins/gradle-cpp-1.4.jar
/usr/share/gradle/lib/plugins/gradle-diagnostics-1.4.jar
/usr/share/gradle/lib/plugins/gradle-ear-1.4.jar
/usr/share/gradle/lib/plugins/gradle-ide-1.4.jar
/usr/share/gradle/lib/plugins/gradle-ivy-1.4.jar
/usr/share/gradle/lib/plugins/gradle-javascript-1.4.jar
/usr/share/gradle/lib/plugins/gradle-jetty-1.4.jar
/usr/share/gradle/lib/plugins/gradle-maven-1.4.jar
/usr/share/gradle/lib/plugins/gradle-osgi-1.4.jar
/usr/share/gradle/lib/plugins/gradle-plugins-1.4.jar
/usr/share/gradle/lib/plugins/gradle-publish-1.4.jar
/usr/share/gradle/lib/plugins/gradle-reporting-1.4.jar
/usr/share/gradle/lib/plugins/gradle-scala-1.4.jar
/usr/share/gradle/lib/plugins/gradle-signing-1.4.jar
/usr/share/gradle/lib/plugins/gson.jar
/usr/share/gradle/lib/plugins/jetty-annotations.jar
/usr/share/gradle/lib/plugins/jetty-naming.jar
/usr/share/gradle/lib/plugins/jetty-plus.jar
/usr/share/gradle/lib/plugins/jetty-util.jar
/usr/share/gradle/lib/plugins/jetty.jar
/usr/share/gradle/lib/plugins/js.jar
/usr/share/gradle/lib/plugins/jsp-api-2.1.jar
/usr/share/gradle/lib/plugins/junit4.jar
/usr/share/gradle/lib/plugins/servlet-api-2.5.jar
/usr/share/gradle/lib/plugins/testng.jar