Priority control by RRC Establishment Cause in free5GC

I have a question about the mechanism of priority control by RRC Establishment Cause in free5GC.
In TS23.501, 5.22.2, it is clearly stated that AMF performs priority control using RRC Establishment Cause.

AMF: Following Access Network Connection Establishment, the receipt of the designated Establishment Cause (i.e. high priority access) by the AMF will result in priority handling of the “Initial UE Message” received as part of the Registration procedures of clause 4.2.2 of TS 23.502 [3] and the Service Request procedures of clause 4.2.3 of TS 23.502 [3]. In addition, certain exemptions to Control Plane Congestion and Overload Control are provided as specified in clause 5.19.

The specific value of Establishment Cause is defined in TS24.501 4.5.2.

I have tried to find out where the priority processing of “Initial UE Message” in AMF is implemented in free5GC, but could not figure it out. Do you know if it is implemented in free5GC and if so, could you please tell me which code is applicable?