[jdom-interest] problems with "indent"

[NP]

answering to myself:

two possibile solutions:
1. we must get the reference to the format of the XMLOutputter, then 
setting the indent line-separator parameters, and finally set the format
e.g.

XMLOutputter serializer = new XMLOutputter();                
Format format = serializer.getFormat();
format.setIndent("   ");
format.setLineSeparator("\n");
serializer.setFormat(format);

2. else, simply, using getPrettyFormat() method:
XMLOutputter serializer = new XMLOutputter();
serializer.setFormat(serializer.getFormat().getPrettyFormat())
(getPrettyFormat: two space to indent, and one newline...)