main.java

@MetaInfServices(JavacAnnotationHandler.class)
@HandlerPriority(1024)
public class DetermineListenerTypesProcessor extends JavacAnnotationHandler<DetermineListenerTypes> {
    @Override
    public void handle(AnnotationValues<DetermineListenerTypes> av, JCTree.JCAnnotation jca, JavacNode jn) {
        JavacNode parent = jn.up();
        JCTree.JCClassDecl classDecl = (JCClassDecl) parent.get();
        
        for (JCTree tree : classDecl.defs) {
            if (tree instanceof JCTree.JCMethodDecl) {
                JCTree.JCMethodDecl methodDecl = (JCTree.JCMethodDecl) tree;

                System.out.println(methodDecl);
                JCTree.JCBlock body = methodDecl.getBody();

                body.accept(new TreeScanner() {
                    @Override
                    public void visitApply(JCTree.JCMethodInvocation methdocall) {
                        if (methdocall.meth instanceof JCTree.JCFieldAccess) {
                            JCTree.JCFieldAccess m = (JCTree.JCFieldAccess) methdocall.meth;

                            //TODO check type!
                            if (m.name.contentEquals("registerListener")) {
                                List<JCTree.JCExpression> methodcallargs = methdocall.getArguments();
                                if (methodcallargs.size() == 1) {
                                    JCTree.JCExpression arg0 = methodcallargs.get(0);
                                    if (arg0 instanceof JCTree.JCLambda) {
                                        JCTree.JCLambda lambda = (JCTree.JCLambda) arg0;

                                        ListBuffer<JCTree.JCExpression> newargs = new ListBuffer<>();
                                        newargs.add(lambda);

                                        JCTree.JCFieldAccess arg1
                                            = jn.getTreeMaker().Select(
                                                lambda.params.get(0).vartype,
                                                jn.toName("class")
                                            );
                                        newargs.add(arg1);
                                        methdocall.args = newargs.toList();
                                    }
                                }

                            }
                        }
                        super.visitApply(methdocall);
                    }
                });
            }
        }
    }
}