Call methods of map directly it ceilingKey() and floorKey() and remove unused import

h2/src/main/org/h2/mvstore/db/TransactionStore.java

@@ -1351,7 +1351,7 @@ public class TransactionStore {
             key = map.ceilingKey(key);
             while (key != null && get(key) == null) {
                 // Use higherKey() for the next attempts, otherwise we'll get an infinite loop
-                key = higherKey(key);
+                key = map.higherKey(key);
             }
             return key;
         }
@@ -1384,7 +1384,7 @@ public class TransactionStore {
             key = map.floorKey(key);
             while (key != null && get(key) == null) {
                 // Use lowerKey() for the next attempts, otherwise we'll get an infinite loop
-                key = lowerKey(key);
+                key = map.lowerKey(key);
             }
             return key;
         }

h2/src/test/org/h2/test/store/TestTransactionStore.java

@@ -19,7 +19,6 @@ import org.h2.mvstore.DataUtils;
 import org.h2.mvstore.MVMap;
 import org.h2.mvstore.MVStore;
 import org.h2.mvstore.db.TransactionStore;
-import org.h2.mvstore.db.ValueDataType;
 import org.h2.mvstore.db.TransactionStore.Change;
 import org.h2.mvstore.db.TransactionStore.Transaction;
 import org.h2.mvstore.db.TransactionStore.TransactionMap;