static RequestHeaders of(HttpMethod method, String path,
                             CharSequence name, Object value) {
        return builder(method, path).addObject(name, value)
                                    .build();
    }
Returns a new {@link RequestHeaders} with the specified {@link HttpMethod}, {@code path} and
an additional header. The value is converted into a {@link String} as explained in
<a href="HttpHeaders.html#object-values">Specifying a non-String header value</a>.
core/src/main/java/com/linecorp/armeria/common/RequestHeaders.java