code: public TableKeysAndAttributes withHashOnlyKeys(String hashKeyName, Object ... hashKeyValues) {
          if (hashKeyName == null)
              throw new IllegalArgumentException();
          PrimaryKey[] primaryKeys = new PrimaryKey[hashKeyValues.length];
          for (int i=0; i < hashKeyValues.length; i++)
              primaryKeys[i] = new PrimaryKey(hashKeyName, hashKeyValues[i]);
          return withPrimaryKeys(primaryKeys);
      }
docs: Used to specify multiple hash-only primary keys.
  @param hashKeyName hash-only key name
  @param hashKeyValues a list of hash key values