SNMP without management interface

you know trap-source does not change ip in ip header, don't you?

e.g.

 config (trap-source none)

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list sys management-ip
sys management-ip 192.168.1.11/24 { }

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list sys snmp trap-source
sys snmp {
    trap-source none
}

 test (trap-source none)

[root@centos1 ~] tcpdump -nni eth0 -X port 162
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
15:56:27.520464 IP 192.168.1.11.40940 > 172.28.24.1.162:  Trap(30)  .1.3.6.1.4.1.3375.2.4 192.168.1.11 enterpriseSpecific s=2 126594
        0x0000:  4500 0049 0000 4000 4011 b4d3 c0a8 010b  E..I..@.@.......
        0x0010:  ac1c 1801 9fec 00a2 0035 bbce 302b 0201  .........5..0+..
        0x0020:  0004 0670 7562 6c69 63a4 1e06 092b 0601  ...public....+..
        0x0030:  0401 9a2f 0204 4004 c0a8 010b 0201 0602  .../..@.........
        0x0040:  0102 4303 01ee 8230 00                   ..C....0.

 config (trap-source 172.28.24.11)

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list sys management-ip
sys management-ip 192.168.1.11/24 { }

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list sys snmp trap-source
sys snmp {
    trap-source 172.28.24.11
}

 test (trap-source 172.28.24.11)

[root@centos1 ~] tcpdump -nni eth0 -X port 162
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
15:56:52.218821 IP 192.168.1.11.50373 > 172.28.24.1.162:  Trap(29)  .1.3.6.1.4.1.3375.2.4 172.28.24.11 enterpriseSpecific s=2 2259
        0x0000:  4500 0048 0000 4000 4011 b4d4 c0a8 010b  E..H..@.@.......
        0x0010:  ac1c 1801 c4c5 00a2 0034 e0d0 302a 0201  .........4..0*..
        0x0020:  0004 0670 7562 6c69 63a4 1d06 092b 0601  ...public....+..
        0x0030:  0401 9a2f 0204 4004 ac1c 180b 0201 0602  .../..@.........
        0x0040:  0102 4302 08d3 3000                      ..C...0.