public BodyPartBuilder content(Path path, int bufferSize) {
        requireNonNull(path, "path");
        return content(StreamMessage.builder(path).bufferSize(bufferSize).build());
    }
Adds the specified {@link Path} as a body part content.
The specified {@code bufferSize} is used to create a buffer and the buffer is used to read data from
the {@link Path}.
core/src/main/java/com/linecorp/armeria/common/multipart/BodyPartBuilder.java