Update NEXT_CHANGELOG with detailed breaking changes for 3.4.1 (#1449)

## Summary
Expand the BREAKING CHANGES section in NEXT_CHANGELOG.md with full
details of metadata JDBC spec compliance changes for 3.4.1.

### Changes
- Restructured from numbered list to detailed bullet points with
migration guidance
- Added missing breaking changes: empty types array, information_schema
inclusion, getPrimaryKeys/getImportedKeys empty ResultSet,
UPDATE_RULE/DELETE_RULE semantics
- Added "Enhancements & New Features" section for the unified metadata
backend
- Moved geospatial default-enabled change into breaking changes section

This pull request was AI-assisted by Isaac.

---------

Signed-off-by: Gopal Lal <gopal.lal@databricks.com>

Author: gopalldb

NEXT_CHANGELOG.md

@@ -2,19 +2,44 @@
 
 ## [Unreleased]
 
-### BREAKING CHANGES in 3.4.1
+### BREAKING CHANGES in 3.4.1 — Metadata JDBC Spec Compliance
 
-1. **`getTables()`: Percent sign (`%`) in catalog argument is now treated as a literal character, not a wildcard.** Previously returned all tables; now returns zero rows unless a catalog named "%" exists. JDBC spec: catalog is an exact-match parameter, not a pattern. Migration: Pass `null` to search all catalogs.
+This release unifies metadata behavior across Thrift and SQL Exec API backends
+using SQL SHOW commands for all metadata operations on SQL warehouses. Several
+non-spec-compliant behaviors have been corrected. Review the changes below before
+upgrading. These changes do not affect metadata on All-Purpose Clusters.
 
-2. **`getColumnTypeName()`: DECIMAL columns now return `"DECIMAL"` without precision/scale** (e.g., `"DECIMAL"` not `"DECIMAL(10,2)"`). Use `getPrecision()` and `getScale()` for numeric constraints. JDBC spec: `getColumnTypeName()` returns the base type name only.
+* **`getTables`/`getColumns`/`getSchemas`: Catalog parameter is now treated as
+  an exact-match identifier per JDBC spec.** Passing `%` or wildcard patterns as
+  catalog previously returned results across all catalogs.
+  Use `null` to search all catalogs.
 
-3. **For DBSQL warehouses, metadata operations are now powered by SHOW SQL commands.** SQL Exec API mode already was powered by SHOW commands, now the same is true for Thrift server mode as well. To revert to native Thrift metadata RPCs, set `UseQueryForMetadata` to `0`.
+* **`getTables` with empty types array: Now returns zero rows per JDBC spec.**
+  Use `null` to return all types.
 
-4. **Native geospatial type support (`GEOMETRY` and `GEOGRAPHY`) is now enabled by default.** `getObject()` now returns `IGeometry`/`IGeography` instances instead of EWKT strings. Set `EnableGeoSpatialSupport=0` to restore the previous behavior.
+* **`getSchemas`: Now includes `information_schema` in results.** Excludes
+  `global_temp` schema (previously returned by Thrift for all catalogs).
+
+* **`getPrimaryKeys`/`getImportedKeys`/`getCrossReference` with non-existent
+  catalog, schema, or table: Now returns empty `ResultSet` instead of throwing
+  `SQLException`.**
+
+* **`getImportedKeys` `UPDATE_RULE`/`DELETE_RULE`: Now returns `3` (`NO_ACTION`)
+  instead of `0` (`CASCADE`) for Thrift, and `3` instead of `null` for SEA.**
+  This reflects that Unity Catalog foreign keys are informational and non-enforced.
+
+* **Native geospatial type support (`GEOMETRY` and `GEOGRAPHY`) is now enabled
+  by default.** `getObject()` now returns `IGeometry`/`IGeography` instances
+  instead of EWKT strings. Set `EnableGeoSpatialSupport=0` to restore the
+  previous behavior.
 
 ### Added
+- Metadata operations now use SQL SHOW commands for both Thrift and SEA backends,
+  ensuring consistent behavior for SQL warehouses regardless of underlying
+  protocol. To revert to native Thrift metadata RPCs, set `UseQueryForMetadata=0`.
 
 ### Updated
+- `getColumnTypeName()` for DECIMAL columns now preserves precision/scale suffix (e.g., `"DECIMAL(10,2)"`) consistently across both Thrift and SEA backends.
 - `EnableGeoSpatialSupport` no longer requires `EnableComplexDatatypeSupport=1`. Geospatial types (GEOMETRY, GEOGRAPHY) can now be enabled independently of complex type support (ARRAY, MAP, STRUCT).
 - Arrow schema deserialization failures (Thrift metadata path) now surface a dedicated driver error code `ARROW_SCHEMA_PARSING_ERROR` (vendor code `22000`) and a proper SQLSTATE `22000` (Data Exception) on the thrown `SQLException`, instead of the generic `RESULT_SET_ERROR` (1004) and the enum name as SQLSTATE. The exception message is unchanged.
 - When a Statement is re-executed, the previous server-side operation is now explicitly closed before starting the new execution, preventing orphaned server-side operations when Statements are reused.