fix(connector): type assertGenericMap keys as Object for shaded/non-shaded Avro

Follow-up to the testSchema Avro tolerance fix. After normalizing non-shaded
Avro arrays to shaded, testSchema failed one layer deeper at assertGenericMap:

  ClassCastException: org.apache.avro.util.Utf8 cannot be cast to
  org.apache.pulsar.shade.org.apache.avro.util.Utf8

A map column (e.g. map<text,double>) comes back from Pulsar as a plain
java.util.Map whose keys are non-shaded Avro Utf8. The parameter type
Map<Utf8,Object> (shaded Utf8) made the compiler insert a checkcast to the
shaded Utf8 on getKey(), which threw even though keys are compared via
toString(). Type the parameter as Map<Object,Object> (as assertMapsEqual
already does) so no checkcast is inserted.

Top-level maps (ymap, ymapoftuple) are the only ones needing this -- maps
nested inside arrays (e.g. zmap inside ysetofudt) are already converted to
shaded by the binary round-trip in normalizeToShadedAvro.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Madhavan

connector/src/test/java/com/datastax/oss/pulsar/source/PulsarCassandraSourceTests.java

@@ -760,7 +760,11 @@ public void testSchema(String ksName) throws InterruptedException, IOException {
         }
     }
 
-    void assertGenericMap(String field, Map<Utf8, Object> gm) {
+    // Keys are typed as Object (not the shaded Utf8): a map column value comes back from Pulsar as a
+    // plain java.util.Map whose keys may be non-shaded Avro Utf8, and a Map<Utf8,Object> parameter
+    // would make the compiler insert a checkcast to the shaded Utf8 on getKey() that throws. Keys are
+    // compared via toString() to tolerate either Avro flavor.
+    void assertGenericMap(String field, Map<Object, Object> gm) {
         switch (field) {
             case "map":
                 log.debug("field={} gm={}", field, gm);