public SELF preflightResponseHeader(CharSequence name, Iterable<?> values) {
        requireNonNull(name, "name");
        requireNonNull(values, "values");
        checkArgument(!Iterables.isEmpty(values), "values should not be empty.");
        final ImmutableList.Builder builder = new Builder();
        int i = 0;
        for (Object value : values) {
            if (value == null) {
                throw new NullPointerException("value[" + i + ']');
            }
            builder.add(value);
            i++;
        }
        preflightResponseHeaders.put(HttpHeaderNames.of(name), new ConstantValueSupplier(builder.build()));
        return self();
    }
Specifies HTTP response headers that should be added to a CORS preflight response.

<p>An intermediary like a load balancer might require that a CORS preflight request
have certain headers set. This enables such headers to be added.

@param name the name of the HTTP header.
@param values the values for the HTTP header.
@return {@code this} to support method chaining.
core/src/main/java/com/linecorp/armeria/server/cors/AbstractCorsPolicyBuilder.java