mysql(UTF-8)导出txt后，再导入HDFS编码不能为GB18030

求助mysql(UTF-8)导出txt不能转成GB18030，看来不是导出问题，是导入HDFS编码不能为GB18030

Start by reproducing the reported flow: export UTF-8 data from MySQL to a TXT file, then import it into HDFS while requesting GB18030 encoding. Investigate the DataX import path for where the encoding is configured or rejected. Done means the import accepts GB18030 and the resulting HDFS data has the expected encoding, with a regression test if the project provides one.

Written by the indexing model from the issue text.