Man pages matching name tshttptxnparentproxyset in section 3ts:

TSHttpTxnParentProxySet.3ts.en	debian 10 / trafficserver-dev
TSHttpTxnParentProxySet.3ts.en	debian 11 / trafficserver-dev
TSHttpTxnParentProxySet.3ts.en	debian 12 / trafficserver-dev