Set default metrics_labels to #{}

Author: mkuratczyk

src/ra_server.erl

@@ -381,6 +381,7 @@ init(#{id := Id,
                uid = UId,
                log_id = LogId,
                metrics_key = MetricKey,
+               metrics_labels = #{},
                machine = Machine,
                machine_version = LatestMacVer,
                machine_versions = [{SnapshotIdx, EffectiveMacVer}],

test/ra_server_SUITE.erl

@@ -2442,6 +2442,7 @@ leader_received_append_entries_reply_with_stale_last_index(_Config) ->
                uid = <<"n1">>,
                log_id = <<"n1">>,
                metrics_key = n1,
+               metrics_labels = #{},
                machine = {machine, ra_machine_simple,
                             #{simple_fun => ?MACFUN,
                               initial_state => <<>>}}, % just keep last applied value
@@ -2500,6 +2501,7 @@ leader_receives_install_snapshot_result(_Config) ->
                uid = <<"n1">>,
                log_id = <<"n1">>,
                metrics_key = n1,
+               metrics_labels = #{},
                machine = {machine, ?FUNCTION_NAME, #{}},
                machine_version = 0,
                machine_versions = [{0, 0}],
@@ -3166,6 +3168,7 @@ base_state(NumServers, MacMod) ->
                uid = <<"n1">>,
                log_id = <<"n1">>,
                metrics_key = n1,
+               metrics_labels = #{},
                machine = {machine, MacMod, #{}}, % just keep last applied value
                machine_version = 0,
                machine_versions = [{0, 0}],