static String getTag() {
        if (IS_DEBUG_BUILD) {
            String className = ProvisionLogger.class.getName();

            StackTraceElement[] trace = Thread.currentThread().getStackTrace();
            if (trace == null) {
                return TAG;
            }

            boolean thisClassFound = false;
            for (StackTraceElement item : trace) {
                if (item.getClassName().equals(className)) {
                    // we are at the current class, keep eating all items from this
                    // class.
                    thisClassFound = true;
                    continue;
                }

                if (thisClassFound) {
                    // This is the first instance of another class, which is most
                    // likely the caller class.
                    return TAG + String.format(
                            "[%s(%s): %s]", item.getFileName(), item.getLineNumber(),
                            item.getMethodName());
                }
            }
        }
        return TAG;
    }
Walks the stack trace to figure out where the logging call came from.
engine/src/main/java/com/oasisfeng/island/provisioning/task/ProvisionLogger.java