netty*.dll files remain in %TMP% folder

[seal-tf]

Version: Logstash 6.1.2 (also tried with 6.5.1)
Operating System: Windows 2012R2

Problem: On a customer Windows server, the C: disc was full and the application(s) stopped working properly. The cause was a lot of dll files in the %TEMP% directory.
Reason: Every time logstash.bat is started, the java process creates a DLL file netty_tcnative_windows_x86_<randomnumber>.dll in the %TEMP% directory and never cleans up.

As a workaround we added the following lines in logstash.bat:

rem workaround to delete netty_tcactive_windows_x86_<randomnumber>.dll files in %TEMP%
del /F "%TEMP%\netty_tcnative_windows_x86_*.dll"