Resource copying not using specified encoding

Overnight our Jenkins builds stopped working. On investigation we found that maven-resources-plugin version used yesterday was 3.1.0 (which worked fine) and today it was using 3.2.0.

The stacktrace produced by adding the "e" switch to the maven command line had the following root cause (truncated for brevity):-

Caused by: java.nio.charset.MalformedInputException: Input length = 1
at java.nio.charset.CoderResult.throwException (CoderResult.java:281)
at sun.nio.cs.StreamDecoder.implRead (StreamDecoder.java:339)
at sun.nio.cs.StreamDecoder.read (StreamDecoder.java:178)
at java.io.InputStreamReader.read (InputStreamReader.java:184)
at java.io.BufferedReader.read1 (BufferedReader.java:210)
at java.io.BufferedReader.read (BufferedReader.java:286)
at java.io.BufferedReader.fill (BufferedReader.java:161)
at java.io.BufferedReader.read (BufferedReader.java:182)
at org.apache.maven.shared.filtering.BoundedReader.read (BoundedReader.java:85)
at org.apache.maven.shared.filtering.MultiDelimiterInterpolatorFilterReaderLineEnding.read (MultiDelimiterInterpolatorFilterReaderLineEnding.java:235)
at org.apache.maven.shared.filtering.MultiDelimiterInterpolatorFilterReaderLineEnding.read (MultiDelimiterInterpolatorFilterReaderLineEnding.java:197)
at java.io.Reader.read (Reader.java:140)
at org.apache.maven.shared.utils.io.IOUtil.copy (IOUtil.java:199)

After a google search told us this was an encoding issue, we added the following to the maven command line, but this made no difference:

-Dproject.build.sourceEncoding=UTF-8 -Dproject.reporting.outputEncoding=UTF-8

The maven build log has these info messsage just before the error:

[INFO] — maven-resources-plugin:3.2.0:resources (default-cli) @ uniworks —
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Using 'UTF-8' encoding to copy filtered properties files.
[INFO] Copying 430 resources

We only 'fixed' the problem by specifying version 3.1.0 of the plugin in the projects POM 'pluginManagement' section.