default List<CompletableFuture<Boolean>> exists(List<Get> gets) {
    return get(toCheckExistenceOnly(gets)).stream()
      .<CompletableFuture<Boolean>> map(f -> f.thenApply(r -> r.getExists())).collect(toList());
  }
Test for the existence of columns in the table, as specified by the Gets.
<p>
This will return a list of booleans. Each value will be true if the related Get matches one or
more keys, false if not.
<p>
This is a server-side call so it prevents any data from being transferred to the client.
@param gets the Gets
@return A list of {@link CompletableFuture}s that represent the existence for each get.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTable.java