Does not work with JDK 8 bsed project

The plugin is built on Java 11, so not possible to use with a project using jdk 8.

Throws exception,

[ERROR] Failed to execute goal se.kth.castor:depclean-maven-plugin:1.1.0:depclean (default) on project idsk-commons-media: Execution default of goal se.kth.castor:depclean-maven-plugin:1.1.0:depclean failed: An API incompatibility was encountered while executing se.kth.castor:depclean-maven-plugin:1.1.0:depclean: java.lang.NoSuchMethodError: java.nio.ByteBuffer.limit(I)Ljava/nio/ByteBuffer;

[cesarsotovalero]

Minor release is coming soon…

[amottier]

I get the same issue with version 1.1.1 so I tried to investigate a little bit more.

Error is related probably to usage of java.nio.ByteBuffer in: https://github.com/castor-software/depclean/blob/master/depclean-core/src/main/java/se/kth/depclean/core/analysis/asm/ConstantPoolParser.java

A comment mention a workaround to this issue but is not implemented.

I run javap -verbose ConstantPoolParser on ConstantPoolParser.class packaged in depclean-core-1.1.1.jar and get the following output:

  minor version: 0
  major version: 52

According to https://en.wikipedia.org/wiki/Java_class_file#General_layout this confirm that this is some byte code targeting Java 8 even if META-INF/MANIFEST.MF packaged in depclean-core-1.1.1.jar mention Build-Jdk: 15.0.1: JDK 15 can generate byte code for Java 8.

An explanation about this behavior can be found in https://github.com/eclipse/jetty.project/issues/3244#issuecomment-495322586

Actually current pom.xml specify source and target (https://github.com/castor-software/depclean/blob/master/pom.xml#L19) but if Java 9 or higher is used to build the project it should specify the release option (maven.compiler.release) see https://stackoverflow.com/a/43103038/2440340

I will shortly create a pull request that fix the issue and allow successful build on Java 9 or higher (but note that build will failed with Java 8) with error [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project depclean-core: Fatal error compiling: invalid flag: --release -> [Help 1])

I’m not sure if there is an easy solution to allow build of the project with both Java 8 and Java 9+ versions. I guess that requiring Java 9+ version for building is not a big issue and that compatibility with Java 8+ version is what is important here.