@Override public byte[] putIfAbsent(Bytes key, byte[] value) { Objects.requireNonNull(key, "key cannot be null"); byte[] rtn; if (value == null) { rtn = blockingStub.delete(POJOUtils.buildOperand(key, new byte[0])).getValue().toByteArray(); } else { rtn = blockingStub.putIfAbsent(POJOUtils.buildOperand(key, value)).getValue().toByteArray(); } if (null == rtn || rtn.length == 0) { return null; } return rtn; }