public static <T> ThriftListenableFuture<T> completedFuture(@Nullable T value) {
        final ThriftListenableFuture<T> future = new ThriftListenableFuture<>();
        future.onComplete(value);
        return future;
    }
Returns a new {@link ThriftListenableFuture} instance that has its value set immediately.
thrift/thrift0.13/src/main/java/com/linecorp/armeria/common/thrift/ThriftListenableFuture.java