Convert list objects to a set of statistical object mapping (map), collectors.reducing

1. Currently there are List < ReportDetail >
2.ReportDetail {key,cnt1,cnt2}
3. Need to convert List < ReportDetail > to Map < Key,Report >
4.Report {key,totalCnt1,totalCnt2}
5. Please tell me how to write the stream operation using JDK8.

Mar.15,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1ea7c5b-1e82.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1ea7c5b-1e82.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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