Make Connection.setReadOnly a no-op instead of throwing

NEXT_CHANGELOG.md

@@ -19,6 +19,7 @@
 - Fixed `getColumns()` flooding the `DriverManager` log writer with caught-and-recovered `Invalid column index` stack traces.
 - Fixed timezone-shifted TIMESTAMP values when retrieving nested complex types (STRUCT/ARRAY/MAP) with `EnableComplexDatatypeSupport=1`.
 - Fixed `DatabricksDatabaseMetaData.supportsBatchUpdates()` always returning `false`, which caused batch-aware JDBC clients (e.g. Apache Hop) to skip `executeBatch()` and fall back to one INSERT per row. It now returns `true` when `EnableBatchedInserts=1`, so those clients use the optimized multi-row INSERT path.
+- Fixed `Connection.setReadOnly(true)` throwing `DatabricksSQLFeatureNotSupportedException`, which broke clients (e.g. Trino/Starburst GenericJDBC, HikariCP, DBCP) that call it during connection initialization. Per the JDBC spec, `setReadOnly` is a hint the driver may ignore; it is now a no-op and `isReadOnly()` continues to return `false`.
 
 ---
 *Note: When making changes, please add your change under the appropriate section

src/main/java/com/databricks/jdbc/api/impl/DatabricksConnection.java

@@ -466,12 +466,14 @@ public DatabaseMetaData getMetaData() throws SQLException {
 
   @Override
   public void setReadOnly(boolean readOnly) throws SQLException {
-    LOGGER.debug("public void setReadOnly(boolean readOnly)");
+    LOGGER.debug("public void setReadOnly(boolean readOnly = {})", readOnly);
     throwExceptionIfConnectionIsClosed();
-    if (readOnly) {
-      throw new DatabricksSQLFeatureNotSupportedException(
-          "Databricks OSS JDBC does not support readOnly mode.");
-    }
+    // Per the JDBC spec, setReadOnly is a hint used to enable database optimizations. The
+    // Databricks
+    // backend does not enforce a connection-level read-only mode, so this is treated as a no-op
+    // rather than throwing. isReadOnly() continues to report false since the hint is not enforced.
+    // Throwing here breaks common clients (e.g. HikariCP, DBCP, Trino/Starburst) that call
+    // setReadOnly(true) during connection initialization.
   }
 
   @Override

src/test/java/com/databricks/jdbc/api/impl/DatabricksConnectionTest.java

@@ -625,9 +625,11 @@ void testTranslationIsolation() throws SQLException {
   void testReadOnlyAndAbort() throws SQLException {
     connection = new DatabricksConnection(connectionContext, databricksClient);
     connection.open();
+    // setReadOnly is a JDBC hint; the driver does not enforce read-only mode, so both values are
+    // accepted as no-ops (see JDBC spec). isReadOnly() continues to report false.
     assertDoesNotThrow(() -> connection.setReadOnly(false));
-    assertThrows(
-        DatabricksSQLFeatureNotSupportedException.class, () -> connection.setReadOnly(true));
+    assertDoesNotThrow(() -> connection.setReadOnly(true));
+    assertFalse(connection.isReadOnly());
     ExecutorService executorService = Executors.newFixedThreadPool(1);
     assertDoesNotThrow(() -> connection.abort(executorService));
     connection.close();