P-Access-Network-Info header cannot be parsed as a list or multiple PANIs is not accepted.

[xhoaluu]

syntax for P-Access-Network-Info:

P-Access-Network-Info = P-Access-Network-Info HCOLON
access-net-spec *(COMMA access-net-spec)
access-net-spec = (access-type / access-class) *(SEMI access-info)
access-type = "IEEE-802.11" / "IEEE-802.11a" / "IEEE-802.11b" / "IEEE-802.11g" /
"IEEE-802.11n" / "3GPP-GERAN" / "3GPP-UTRAN-FDD" / "3GPP-UTRAN-TDD" /
"3GPP-E-UTRAN-FDD" / "3GPP-E-UTRAN-TDD" / "ADSL" / "ADSL2" / "ADSL2+" /
"RADSL" / "SDSL" / "HDSL" / "HDSL2" / "G.SHDSL" / "VDSL" / "IDSL" /
"3GPP2-1X" / "3GPP2-1X-Femto" / "3GPP2-1X-HRPD" / "3GPP2-UMB" / "DOCSIS"
/ "IEEE-802.3" / "IEEE-802.3a" / "IEEE-802.3e" / "IEEE-802.3i" / "IEEE802.3j"
/ "IEEE-802.3u" / "IEEE-802.3ab"/ "IEEE-802.3ae" / "IEEE802.3ak"
/ "IEEE-802.3aq" / "IEEE-802.3an" / "IEEE-802.3y" / "IEEE802.3z"
/ GPON/ XGPON1/ "GSTN"/ token
...access-class = "3GPP-GERAN" / "3GPP-UTRAN" / "3GPP-E-UTRAN" / "3GPP-WLAN" / "3GPP-GAN"
/ "3GPP-HSPA" / token
np = "network-provided"
access-info = cgi-3gpp / utran-cell-id-3gpp / dsl-location / i-wlan-node-id / ci-3gpp2
/ ci-3gpp2-femto / eth-location / fiber-location / np/ gstn-location /
extension-access-info
extension-access-info = gen-value
cgi-3gpp = "cgi-3gpp" EQUAL (token / quoted-string)
utran-cell-id-3gpp = "utran-cell-id-3gpp" EQUAL (token / quoted-string)
i-wlan-node-id = "i-wlan-node-id" EQUAL (token / quoted-string)
dsl-location = "dsl-location" EQUAL (token / quoted-string)
eth-location = "eth-location" EQUAL (token / quoted-string)
fiber-location = "fiber-location" EQUAL (token / quoted-string)
ci-3gpp2 = "ci-3gpp2" EQUAL (token / quoted-string)
ci-3gpp2-femto = "ci-3gpp2-femto" EQUAL (token / quoted-string)
gstn-location = "gstn-location" EQUAL (token / quoted-string)

And https://tools.ietf.org/html/rfc3261#section-7.3.1 states that:

"Multiple header field rows with the same field-name MAY be present in
a message if and only if the entire field-value for that header field
is defined as a comma-separated list (that is, if follows the grammar
defined in Section 7.3)."

This means that using multiple P-Access-Newtork-Info headers is
valid syntax.