Maven clean command: java.util.Collections.UnmodifiableRandomAccessList to property of type java.util.ArrayList
I had the same issue with Maven 3.6.0 as well. The problem seems to be a bug in the plugin, because it disappears starting from the plugin version 3.0.4. So the solution for me was to specify the version in the pom.xml:
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>findbugs-maven-plugin</artifactId>
<version>3.0.4</version>
<configuration>
<failOnError>${maven.findbugs.failure.strict}</failOnError>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
Using mvn version 3.3.x might solve this problem. I got this error with 3.6.x.