@Override
	protected void writeChunk(final byte[] buffer, final int offset, final int length) throws IOException {
		if (length > 0 && buffer[offset] == '.' && this.startOfLine) {
			// add extra dot (the first of the pair)
			this.out.write('.');
		}
		super.writeChunk(buffer, offset, length);
	}
Overrides super writeChunk in order to add a "." if the previous chunk ended
with a new line and a new chunk starts with "."

@see CRLFOutputStream#writeChunk(byte[], int, int)
src/main/java/de/gessnerfl/fakesmtp/smtp/io/ExtraDotOutputStream.java