public static byte[] jsonNodeToBinary(JsonNode node, String about) {
        try {
            byte[] value = node.binaryValue();
            if (value == null) {
                throw new IllegalArgumentException(about + ": expected Base64-encoded binary data.");
            }

            return value;
        } catch (IOException e) {
            throw new UncheckedIOException(about + ": unable to retrieve Base64-encoded binary data", e);
        }
    }
Copy a byte buffer into an array.  This will not affect the buffer's
position or mark.
clients/src/main/java/org/apache/kafka/common/protocol/MessageUtil.java