default CompletableFuture<Boolean> exists(Get get) {
    return get(toCheckExistenceOnly(get)).thenApply(r -> r.getExists());
  }
Test for the existence of columns in the table, as specified by the Get.
<p>
This will return true if the Get matches one or more keys, false if not.
<p>
This is a server-side call so it prevents any data from being transfered to the client.
@return true if the specified Get matches one or more keys, false if not. The return value will
        be wrapped by a {@link CompletableFuture}.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncTable.java