code: @Override
      public CompletableFuture<Map<String, StreamConfiguration>> listStreamsInScope(final String scopeName) {
          return getScope(scopeName).listStreamsInScope().thenCompose(streams -> {
              HashMap<String, CompletableFuture<Optional<StreamConfiguration>>> result = new HashMap<>();
              for (String s : streams) {
                  Stream stream = getStream(scopeName, s, null);
                  result.put(stream.getName(), 
                          Futures.exceptionallyExpecting(stream.getConfiguration(), 
                                  e -> e instanceof StoreException.DataNotFoundException, 
                                  null)
                          .thenApply(Optional::ofNullable));
              }
              return Futures.allOfWithResults(result)
                      .thenApply(x -> {
                          return x.entrySet().stream().filter(y -> y.getValue().isPresent())
                           .collect(Collectors.toMap(Map.Entry::getKey, entry -> entry.getValue().get()));
                      });
          });
      }
docs: List the streams in scope.
  
  @param scopeName Name of scope
  @return A map of streams in scope to their configs.