Paragraphs located in the same list item are merged

When parsing markdown/1.2 content, the paragraphs of a list item are merged without any separator, so the words are glued together.

Steps to reproduce

Parse:

* a

  para2

Result

onWord [a]
onWord [para2]

which is rendered as apara2 (and as * apara2 when rendered back to Markdown).

Expected

The paragraphs stay separated (e.g. with a new line, or as separate blocks as done by the XWiki 2.1 syntax).