SessionDescription::to_string creates invalid rtpmap attribute

[babymotte]

I have the following SDP file:

v=0
o=- 123456 123456 IN IP4 192.168.178.118
s=SAP Tester
i=2 channels: Left, Right
c=IN IP4 239.69.26.110/32
t=0 0
a=keywds:Dante
a=recvonly
m=audio 5004 RTP/AVP 97
a=rtpmap:97 L24/48000/2
a=ptime:1
a=ts-refclk:ptp=IEEE1588-2008:00-1D-C1-FF-FE-53-48-B5:0
a=mediaclk:direct=0

When I parse this using this library and then print it out using the to_string method, I get this:

v=0
o=- 123456 123456 IN IP4 192.168.178.118
s=SAP Tester
i=2 channels: Left, Right
c=IN IP4 239.69.26.110/32
t=0 0
a=keywds:Dante
a=recvonly
m=audio 5004 RTP/AVP 97
a=rtpmap:97 L24/48000 2
a=ptime:1
a=ts-refclk:ptp=IEEE1588-2008:00-1D-C1-FF-FE-53-48-B5:0
a=mediaclk:direct=0

Notice how the a=rtpmap field is formatted differently.

When I publish this SDP on my local network using the SAP protocol and look at the UDP package in wireshark, wireshark tells me that the SDP is malformed because of this. Is this a bug in the library or just an SAP specific dialect the library is not aware of?