Summary
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Remove the undocumented `sun.nio.cs.map` system property that overrides the default charset name/alias mapping.
Problem
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The system property was provided for applications that would break with the fix to JDK-4712786. It was meant to be used for the time being while those applications migrate the definition of `Shift_JIS` from Windows code page 932 encoding to IANA defined `Shift_JIS`. The behavior has been partially broken since JDK 9 and should be removed rather than fixed.
Solution
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Remove the system property from runtime.
Specification
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N/A since the system property was never documented.