Get Query for Retrieving all Keys

What is the equivalent KV client query for performing the following operation to retrieve all keys?

etcdctl get "" --prefix=true

I tried the following query, it didn’t work.

 CompletableFuture<GetResponse> futureResponse =
      client.getKVClient().get(ByteSequence.fromString(""),
          GetOption.newBuilder().withPrefix(ByteSequence.fromString("true")).build());

 GetResponse response = futureResponse.get();

[indrabasak]

Here is a complete example using withRange:

@Override
public Map<String, String> findAllKeys() {
    try {
        ByteSequence key = ByteSequence.fromString("\0");
        GetOption option = GetOption.newBuilder()
                .withSortField(GetOption.SortTarget.KEY)
                .withSortOrder(GetOption.SortOrder.DESCEND)
                .withRange(key)
                .build();

        CompletableFuture<GetResponse> futureResponse =
                client.getKVClient().get(key, option);

        GetResponse response = futureResponse.get();
        if (response.getKvs().isEmpty()) {
            log.info("Failed to retrieve any key.");
            return null;
        }


        Map<String, String> keyValueMap = new HashMap<>();
        for (KeyValue kv : response.getKvs()) {
            keyValueMap.put(kv.getKey().toStringUtf8(),
                    kv.getValue().toStringUtf8());
        }

        log.info("Retrieved " + response.getKvs().size() + " keys.");

        return keyValueMap;

    } catch (Exception e) {
        throw new DatabaseException(
                "Failed to retrieve any key.", e);
    }
}

[xiang90]

we probably need to document this somewhere, or provide a const to make it clear.