@Override
    protected boolean execute(
            CtClass inputClass,
            String inputClassName,
            NewExpr newExpr)
            throws CannotCompileException, NotFoundException {

        String insnClassName = newExpr.getClassName();
        String insnSignature = newExpr.getSignature();

        if (!isMatchConstructorSource(insnClassName, insnSignature)) {
            return false;
        }
        String target = getTarget();

        if (!target.endsWith(";")) {
            target = target + ";";
        }
        String before = isAsBefore() ? target : "";
        String after = isAsAfter() ? target : "";
        String statement = "{" + before + "$_=$proceed($$);" + after + "}";
        String replacement = replaceInstrument(inputClassName, newExpr, statement);

        if (isAsBefore()) {
            Logger.warning(getPrettyName() + " by before: " + replacement
                    + " at " + inputClassName + ".java" + ":" + newExpr.getLineNumber());
        }

        if (isAsAfter()) {
            Logger.warning(getPrettyName() + " by after: " + replacement
                    + " at " + inputClassName + ".java" + ":" + newExpr.getLineNumber());
        }
        return true;
    }
Transform that inserts custom code at the pointcut where constructor is called.
plugin/src/main/groovy/com/didichuxing/tools/droidassist/transform/insert/ConstructorCallInsertTransformer.java