Summary

The jdk.net.URLClassPath.showIgnoredClassPathEntries system property should be documented in the JavaDoc.

Problem

The jdk.net.URLClassPath.showIgnoredClassPathEntries system property was added in JDK-8211941 to assist in debugging of invalid Class-Path attributes in JAR file manifests. It will be mentioned in the Release Notes, but should also be mentioned somewhere more accessible - in the JavaDoc.

Solution

Problems with an invalid Class-Path entry would turn up during classloading. A reasonable place to document the jdk.net.URLClassPath.showIgnoredClassPathEntries property is in ClassLoader.getSystemClassLoader(), which already has an @implNote describing the use of other classloading-related system properties.

Using the @systemProperty tag will allow the property name to be found in the JavaDoc search box.

Specification

--- a/src/java.base/share/classes/java/lang/ClassLoader.java    Fri Apr 26 12:49:51 2019 -0400
+++ b/src/java.base/share/classes/java/lang/ClassLoader.java    Mon Apr 29 14:58:54 2019 -0700
@@ -1893,6 +1893,16 @@
      * otherwise, if unnamed, it will set the class path to the current
      * working directory.
      *
+     * <p> JAR files on the class path may contain a {@code Class-Path} manifest
+     * attribute to specify dependent JAR files to be included in the class path.
+     * {@code Class-Path} entries must meet certain conditions for validity (see
+     * the <a href="{@docRoot}/../specs/jar/jar.html#class-path-attribute">
+     * JAR File Specification</a> for details).  Invalid {@code Class-Path}
+     * entries are ignored.  For debugging purposes, ignored entries can be
+     * printed to the console if the
+     * {@systemProperty jdk.net.URLClassPath.showIgnoredClassPathEntries} system
+     * property is set to {@code true}.
+     *
        * ...
public static ClassLoader getSystemClassLoader()