Merge pull request #1461 from Sreekala-Gopakumar/1406SCCNo

Shared class cache generation update

docs/version0.49.md

@@ -26,6 +26,7 @@
 The following new features and notable changes since version 0.48.0 are included in this release:
 
 - [New binaries and changes to supported environments](#binaries-and-supported-environments)
+- [Change to the shared classes cache generation number](#change-to-the-shared-classes-cache-generation-number)
 
 ## Features and changes
 
@@ -37,6 +38,14 @@ macOS 12 is out of support and is removed from the list of supported platforms.
 
 To learn more about support for OpenJ9 releases, including OpenJDK levels and platform support, see [Supported environments](openj9_support.md).
 
+### Change to the shared classes cache generation number
+
+The shared classes cache generation number is incremented. The increment in the shared classes cache generation number causes the VM to create a new shared classes cache, rather than re-creating or reusing an existing cache.
+
+To save space, all existing shared caches can be removed unless they are in use by an earlier release. For more information, see [Housekeeping](shrc.md#housekeeping) and [`-Xshareclasses`](xshareclasses.md).
+
+The shared classes cache generation number is modified because of a change in the format of ROMClasses that are stored in the shared classes cache. A new flag `J9AccClassIsShared` is added to ROMClasses to indicate whether a ROMClass was loaded from a shared classes cache or from a VM.
+
 ## Known problems and full release information
 
 To see known problems and a complete list of changes between Eclipse OpenJ9 v0.48.0 and v0.49.0 releases, see the [Release notes](https://github.com/eclipse-openj9/openj9/blob/master/doc/release-notes/0.49/0.49.md).