Filter by l4proto doesn't work as expected

[lucaderi]

curl -u admin:admin 'http://localhost:9000/lua/rest/v2/get/flow/active.lua?ifid=14&l4proto=UDP' | jq '.rsp.data | .[] | .protocol'
{
"l7": "HTTP.ntop",
"l4": "TCP"
}
{
"l7": "HTTP.ntop",
"l4": "TCP"
}
{
"l7": "HTTP.ntop",
"l4": "TCP"
}
{
"l7": "HTTP.ntop",
"l4": "TCP"
}
{
"l7": "HTTP.ntop",
"l4": "TCP"
}
{
"l7": "MDNS",
"l4": "UDP"
}
{
"l7": "ICMP",
"l4": "ICMP"
}
{
"l7": "ICMP",
"l4": "ICMP"
}
{
"l7": "TLS",
"l4": "TCP"
}
{
"l7": "SSH",
"l4": "TCP"
}

[MatteoBiscosi]

In the latest ntopng version, the rest api seems working correctly: