public String read() {
            ByteBuffer nextBuffer = content.read();
            if (nextBuffer == null) return null; // end of transmission
            return StandardCharsets.UTF_8.decode(nextBuffer).toString();
        }
Read the next piece of data from this channel, blocking if needed.
If all data is already read, this returns null.
container-core/src/main/java/com/yahoo/container/jdisc/RequestHandlerTestDriver.java