<groovyc> does not provide an option to customize the target bytecode version used by ACG

Although the CompilerConfiguration has a flag called targetBytecode that is used to override the default targetBytecode version determined by groovy compiler, <groovyc> does not provide any option to specify it.

So, if you are using <groovyc> to compile the scripts, the default targetBytecode cannot be overridden. It needs to expose an attribute and connect it to CompilerConfiguration's targetBytecode flag.