Deprecate VM option CheckEndorsedAndExtDirs

Summary

Deprecated the HotSpot VM option CheckEndorsedAndExtDirs. Using the option will generate a warning. The option will be removed in a future release.

Problem

The endorsed standards override mechanism and the extensions mechanism were removed in JDK 9 via JEP 220.

The CheckEndorsedAndExtDirs option is intended to help applications to migrate to JDK 9 and is no longer needed in a future release. This option is disabled by default. However, if it's enabled in the command-line, the VM would check the endorsed and ext directories so that the VM terminates if they exist. These checks are no longer needed in JDK 10 and beyond and can be removed.

This CSR is the first step in the removal -- we need to mark this option as deprecated and print a warning message when it's used. The option itself, and the code that uses it, will be removed in a subsequent JDK release.

Solution

Print a warning message if this option is used.

Specification

diff -r d76a6042f5d7 src/hotspot/share/runtime/arguments.cpp
--- a/src/hotspot/share/runtime/arguments.cpp   Wed Nov 08 09:03:24 2017 -0800
+++ b/src/hotspot/share/runtime/arguments.cpp   Thu Nov 09 11:14:08 2017 -0800
@@ -383,6 +383,7 @@
   { "MinRAMFraction",               JDK_Version::jdk(10),  JDK_Version::undefined(), JDK_Version::undefined() },
   { "InitialRAMFraction",           JDK_Version::jdk(10),  JDK_Version::undefined(), JDK_Version::undefined() },
   { "IgnoreUnverifiableClassesDuringDump", JDK_Version::jdk(10),  JDK_Version::undefined(), JDK_Version::undefined() },
+  { "CheckEndorsedAndExtDirs",      JDK_Version::jdk(10),  JDK_Version::undefined(), JDK_Version::undefined() },

   // --- Deprecated alias flags (see also aliased_jvm_flags) - sorted by obsolete_in then expired_in:
   { "DefaultMaxRAMFraction",        JDK_Version::jdk(8),  JDK_Version::undefined(), JDK_Version::undefined() },