private static int read(ReadableByteChannel src, ByteBuf dst) throws IOException {
        if (src instanceof ScatteringByteChannel) {
            return dst.writeBytes((ScatteringByteChannel) src, dst.writableBytes());
        }

        final int readBytes = src.read(dst.nioBuffer(dst.writerIndex(), dst.writableBytes()));
        if (readBytes > 0) {
            dst.writerIndex(dst.writerIndex() + readBytes);
        }
        return readBytes;
    }
{@link HttpService} to handle a {@link WebOperation}. Mostly inspired by reactive implementation in
{@link AbstractWebFluxEndpointHandlerMapping}.
spring/boot3-actuator-autoconfigure/src/main/java/com/linecorp/armeria/spring/actuate/WebOperationService.java