public <T> ServerBuilder childChannelOption(ChannelOption<T> option, T value) {
        requireNonNull(option, "option");
        checkArgument(!ChannelUtil.prohibitedOptions().contains(option),
                      "prohibited socket option: %s", option);

        option.validate(value);
        childChannelOptions.put(option, value);
        return this;
    }
Sets the {@link ChannelOption} of sockets accepted by {@link Server}.
Note that the previously added option will be overridden if the same option is set again.

<pre>{@code
ServerBuilder sb = Server.builder();
sb.childChannelOption(ChannelOption.SO_REUSEADDR, true)
  .childChannelOption(ChannelOption.SO_KEEPALIVE, true);
}</pre>
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java