auto-flush added (optional)

[idozorenko]

Adds optional auto-flush possibility, so as checkSize() does not have to be called manually.

[adrian-herscu]

Why someone would want not to flush "automatically"?
I solved this by wrapping the stream provided by getMultiPartOutputStreams with a FilterOutputStream like this:

final class CheckedMultipartOutputStream
            extends FilterOutputStream {
            CheckedMultipartOutputStream(final OutputStream out) {
                super(out);
            }

            @Override
            @SneakyThrows
            public void write(final byte[] b)
                throws IOException {
                super.write(b);
                out().checkSize();
            }
....

[alexmojaki]

Thanks guys, and sorry I never responded to this. There was a time when I thought that checkSize being called too eagerly could lead to malformed data, that was a mistake. I have released a version 2.0 in which the method is no longer public and is called automatically.