Iterator<SIPHeader> it = this.headers.iterator();
while (it.hasNext()) {
SIPHeader siphdr = (SIPHeader) it.next();
if (!(siphdr instanceof ContentLength))
encoding.append(siphdr.encode());
}
// Append the unrecognized headers. Headers that are not
// recognized are passed through unchanged.
for ( String unrecognized : this.unrecognizedHeaders) {
encoding.append(unrecognized).append(NEWLINE);