Attempting to gather HP-ICF-POE-MIB with telegraf - cannot join tables

Trying to join the table with IF-MIB:ifTable ifIndex to the last octet in the indices from HP-ICF-POE-MIB, so I can get ifAlias.
Unfortunately, HP-ICF-POE-MIB has a 1. prefix on the index.
Seems I need an oid_index_prefix, can’t find anything similar.

HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.1 = INTEGER: 65
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.2 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.3 = INTEGER: 26
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.4 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.5 = INTEGER: 57
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.6 = INTEGER: 71
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.7 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortCurrent.1.8 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.1 = INTEGER: 539
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.2 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.3 = INTEGER: 538
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.4 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.5 = INTEGER: 544
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.6 = INTEGER: 542
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.7 = INTEGER: 0
HP-ICF-POE-MIB::hpicfPoePethPsePortVoltage.1.8 = INTEGER: 0