removed session_timezone from clearSession()

Author: chernser

client-v2/src/main/java/com/clickhouse/client/api/internal/CommonSettings.java

@@ -143,7 +143,8 @@ public void clearSession() {
         resetOption(ClientConfigProperties.serverSetting(ClickHouseHttpProto.QPARAM_SESSION_ID));
         resetOption(ClientConfigProperties.serverSetting(ClickHouseHttpProto.QPARAM_SESSION_CHECK));
         resetOption(ClientConfigProperties.serverSetting(ClickHouseHttpProto.QPARAM_SESSION_TIMEOUT));
-        resetOption(ClientConfigProperties.serverSetting(ClickHouseHttpProto.QPARAM_SESSION_TIMEZONE));
+        // Do not clean `session_timezone` setting because it is not related to session management and used to
+        // set timezone for consequent queries in some multi-user applications.
     }
 
     /**

client-v2/src/test/java/com/clickhouse/client/SettingsTests.java

@@ -160,7 +160,9 @@ void testQuerySettingsSpecific() throws Exception {
             Assert.assertNull(settings.getSessionId(), "clearSession() must remove session_id");
             Assert.assertNull(settings.getSessionCheck(), "clearSession() must remove session_check");
             Assert.assertNull(settings.getSessionTimeout(), "clearSession() must remove session_timeout");
-            Assert.assertNull(settings.getSessionTimezone(), "clearSession() must remove session_timezone");
+            // session_timezone is not session-management state; it is preserved across clearSession().
+            Assert.assertEquals(settings.getSessionTimezone(), "America/New_York",
+                    "clearSession() must not remove session_timezone");
 
             // Non-session settings are unaffected.
             settings.setDatabase("db1");
@@ -273,7 +275,9 @@ public void testInsertSettingsSpecific() throws Exception {
             Assert.assertNull(settings.getSessionId(), "clearSession() must remove session_id");
             Assert.assertNull(settings.getSessionCheck(), "clearSession() must remove session_check");
             Assert.assertNull(settings.getSessionTimeout(), "clearSession() must remove session_timeout");
-            Assert.assertNull(settings.getSessionTimezone(), "clearSession() must remove session_timezone");
+            // session_timezone is not session-management state; it is preserved across clearSession().
+            Assert.assertEquals(settings.getSessionTimezone(), "Asia/Tokyo",
+                    "clearSession() must not remove session_timezone");
 
             // Non-session settings are unaffected.
             settings.setDatabase("db2");