Java: Add change note.

change-notes/1.24/analysis-java.md

@@ -15,3 +15,11 @@ The following changes in version 1.24 affect Java analysis in all applications.
 
 ## Changes to libraries
 
+* Identification of test classes have been improved. Previously, one of the
+  match conditions would classify any class with a name containing the string
+  "Test" as a test class, but now this matching has been replaced with one that
+  looks for the occurrence of actual unit-test annotations. This affects the
+  general file classification mechanism and thus suppression of alerts, and
+  also any security queries using taint tracking, as test classes act as
+  default barriers stopping taint flow.
+