code: public boolean contains(final AbstractDynamoDbStore store, final StaticBuffer key, final StaticBuffer column) {
          return expectedValues.containsKey(store)
              && expectedValues.get(store).containsKey(key)
              && expectedValues.get(store).get(key).containsKey(column);
      }
docs: Determins whether a particular key and column are part of this transaction
  @param key key to check for existence
  @param column column to check for existence
  @return true if both the key and column combination are in this transaction and false otherwise.