lnd-manageJ (https://github.com/C-Otto/lnd-manageJ/) is now able to parse the custom records lnd uses to provide information about inbound channel fees. There's no need to use lnd v0.18 to read this information.
Example (running with lnd 0.17):
$ curl -s http://localhost:8081/api/channel/841817x723x0/policies { "local" : { "feeRatePpm" : 1000, "baseFeeMilliSat" : "0", "inboundFeeRatePpm" : 0, "inboundBaseFeeMilliSat" : "0", "enabled" : true, "timeLockDelta" : 99, "minHtlcMilliSat" : "1", "maxHtlcMilliSat" : "2540199000" }, "remote" : { "feeRatePpm" : 1000, "baseFeeMilliSat" : "0", "inboundFeeRatePpm" : -500, "inboundBaseFeeMilliSat" : "0", "enabled" : true, "timeLockDelta" : 100, "minHtlcMilliSat" : "1", "maxHtlcMilliSat" : "2540199000" } }
To test this, I created a new node running lnd v0.18.0-beta.rc1 (https://amboss.space/node/025cd50e55b969a418e713b70076333ba1e25929e9e6ec5b937c30a8edc85cc82b) and opened two channels (https://amboss.space/edge/925656849283350529 and https://amboss.space/edge/925587580006891520). Both of these channels charge 1000ppm but also include a discount by setting the inbound fee rate to -500. Feel free to test your software using this node!