@Override
    @FormatMethod
    @SuppressWarnings("FormatStringAnnotation")
    public TransformingRequestPreparation<T, R> content(MediaType contentType, @FormatString String format,
                                                        Object... content) {
        delegate.content(contentType, format, content);
        return this;
    }
Sets the specified {@link ResponseAs} that converts the {@code T} type object into another.
core/src/main/java/com/linecorp/armeria/client/TransformingRequestPreparation.java