Added support of SnapshotRW transaction level

common/src/main/java/tech/ydb/common/transaction/TxMode.java

@@ -9,6 +9,7 @@ public enum TxMode {
 
     SERIALIZABLE_RW,
     SNAPSHOT_RO,
+    SNAPSHOT_RW,
     STALE_RO,
 
     ONLINE_RO,

query/src/main/java/tech/ydb/query/impl/TxControl.java

@@ -16,6 +16,10 @@ class TxControl {
             .setSnapshotReadOnly(YdbQuery.SnapshotModeSettings.getDefaultInstance())
             .build();
 
+    private static final YdbQuery.TransactionSettings TS_SNAPSHOT_RW = YdbQuery.TransactionSettings.newBuilder()
+            .setSnapshotReadWrite(YdbQuery.SnapshotRWModeSettings.getDefaultInstance())
+            .build();
+
     private static final YdbQuery.TransactionSettings TS_STALE = YdbQuery.TransactionSettings.newBuilder()
             .setStaleReadOnly(YdbQuery.StaleModeSettings.getDefaultInstance())
             .build();
@@ -55,6 +59,8 @@ public static YdbQuery.TransactionSettings txSettings(TxMode tx) {
                 return TS_SERIALIZABLE;
             case SNAPSHOT_RO:
                 return TS_SNAPSHOT;
+            case SNAPSHOT_RW:
+                return TS_SNAPSHOT_RW;
             case STALE_RO:
                 return TS_STALE;
             case ONLINE_RO:

table/src/main/java/tech/ydb/table/impl/TxControlToPb.java

@@ -61,9 +61,11 @@ public static YdbTable.TransactionSettings txSettings(TxMode tx) {
                 return TS_ONLINE;
             case ONLINE_INCONSISTENT_RO:
                 return TS_ONLINE_INCONSISTENT;
+
             case NONE:
+            case SNAPSHOT_RW:
             default:
-                return null;
+                throw new IllegalArgumentException("Tx mode " + tx + " is not supported in TableService");
         }
     }
 }