I’ve had a similar problem with an old BungeeCord plugin, which used Gradle 4.10. In my case – it seems like that old Gradle doesn’t work properly with Java 16, so I’ve manually changed contents of gradle/wrapper/gradle-wrapper.properties file to use Gradle 7.0.
Old file:
distributionUrl=https\://services.gradle.org/distributions/gradle-4.10-bin.zip
New file:
distributionUrl=https\://services.gradle.org/distributions/gradle-7.0-bin.zip
Now it works ok, no more Gradle errors.
