itext7 paragraph's vertical alignment: puzzling behaviour

Question

I have this simple code for testing vertical alignment in paragraphs:

Paragraph p = new Paragraph();
p.setBackgroundColor(new DeviceRgb(189, 239, 73));
p.setBorder(new SolidBorder(0.2f));
p.setVerticalAlignment(VerticalAlignment.MIDDLE);
p.add("first line - vertical alignment MIDDLE");
p.add("\n second line");
p.add("\n 3rd line");
document.add(p);

p = new Paragraph();
p.setBackgroundColor(new DeviceRgb(249, 149, 183));
p.setBorder(new SolidBorder(0.2f));
p.setVerticalAlignment(VerticalAlignment.TOP);
p.add("first line - vertical alignment TOP");
p.add("\n second line");
p.add("\n 3rd line");
document.add(p);

p = new Paragraph();
p.setBackgroundColor(new DeviceRgb(149, 189, 253));
p.setBorder(new SolidBorder(0.2f));
p.setVerticalAlignment(VerticalAlignment.BOTTOM);
p.add("first line - vertical alignment BOTTOM");
p.add("\n second line");
p.add("\n 3rd line");
document.add(p);

The result is this:

It seems that only the first Text child is vertically aligned in every Paragraph: if it's the standard behaviour, it's somewhat confusing.

However if I use a Div and add a Paragraph to it and transfer all properties and child elements to the Div, all works fine. Why?