set ContentDisposition

Hello,
Could someone tell me what's wrong with this code
(jigsaw 2.2.2)?

response.setHeader("Content-Disposition", "attachment;
filename=PEWG.zip")

With the debugger, the values I get after this line
are (hope it's understandable):

HttpServletResponse.reply.headers.keys[0]="content-disposition"
HttpServletResponse.reply.headers.values[0].value=null
HttpServletResponse.reply.headers.values[0].isValid=false
HttpServletResponse.reply.headers.values[0].raw=byte[29]
 (the good string)
HttpServletResponse.reply.headers.values[0].roff=0

Why  values[0].value=null when in values[0].raw there
is the right value?

Is that a bug in jigsaw?

Thanks,
Felicia

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