public static Filter createFilterFromArguments(ArrayList<byte[]> filterArguments) {
    Preconditions.checkArgument(filterArguments.isEmpty(), "Expected 0 but got: %s",
      filterArguments.size());
    return new FirstKeyOnlyFilter();
  }
A filter that will only return the first KV from each row.
<p>
This filter can be used to more efficiently perform row count operations.
hbase-client/src/main/java/org/apache/hadoop/hbase/filter/FirstKeyOnlyFilter.java