protected Iterable<ByteBuffer> requestContent() {
        return List.of();
    }
<p>Returns an Iterable for the ByteBuffers that the {@link #dispatch()} method should write to the {@link
Request} once it has {@link #connect() connected}. The default implementation returns an empty list. Because this
method uses the Iterable interface, you can create the ByteBuffers lazily, or provide them as they become
available.</p>

@return The ByteBuffers to write to the Request's ContentChannel.
jdisc_core/src/main/java/com/yahoo/jdisc/handler/RequestDispatch.java