public HttpRequest body(final Parameters params) {
        this.requestBodySupplier = () -> {
            final FormBody.Builder body = new FormBody.Builder();
            if (params != null) {
                for (final ImmutablePair<String, String> param : params) {
                    body.add(param.left, param.right);
                }
            }
            return body.build();
        };
        return this;
    }
sets body to a simple key-value-pair list
main/src/main/java/cgeo/geocaching/network/HttpRequest.java