CASSANDRA-15908: Fix FrozenCollectionsTest
diff --git a/test/unit/org/apache/cassandra/cql3/validation/entities/FrozenCollectionsTest.java b/test/unit/org/apache/cassandra/cql3/validation/entities/FrozenCollectionsTest.java
index ccf8b59..23ac0ff 100644
--- a/test/unit/org/apache/cassandra/cql3/validation/entities/FrozenCollectionsTest.java
+++ b/test/unit/org/apache/cassandra/cql3/validation/entities/FrozenCollectionsTest.java
@@ -557,7 +557,7 @@
         assertInvalidIndexCreationWithMessage("CREATE INDEX ON %s (full(a))", "Cannot create secondary index on the only partition key column");
         assertInvalidIndexCreationWithMessage("CREATE INDEX ON %s (keys(a))", "Cannot create secondary index on the only partition key column");
         assertInvalidIndexCreationWithMessage("CREATE INDEX ON %s (keys(b))", "Cannot create keys() index on frozen column b. " +
-                                                                              "Frozen collections only support indexes on the entire data structure");
+                                                                              "Frozen collections are immutable and must be fully indexed");
 
         createTable("CREATE TABLE %s (a int, b frozen<list<int>>, c frozen<set<int>>, d frozen<map<int, text>>, PRIMARY KEY (a, b))");