java.lang.ClassCastException: [Z cannot be cast to [Ljava.lang.String in reflective toString on model class

I have a model class in java and I overwrote the toString to provide me with a custom toString. The toString uses reflection to find the field names and values and it works when I run it locally via my ide. However when I run it via mvn agents I always seem to get the error:

java.lang.ClassCastException: [Z cannot be cast to [Ljava.lang.String

Here is the toString:

@SneakyThrows
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        Class<?> thisClass = Class.forName(this.getClass().getName());
        Field[] aClassFields = thisClass.getDeclaredFields();
        for (Field f : aClassFields) {
            String fName = f.getName();
            fName = fName.startsWith("_") ? fName.substring(1) : fName;
            if (null != f.get(this)) {
                if (f.get(this) instanceof String || f.get(this) instanceof List) {
                    sb.append(getVariableNameStr(fName, f.get(this).toString()));
                } else {
                    StringBuilder stringArrayStr = new StringBuilder();
                    for (String s : (String[]) f.get(this)) {
                        stringArrayStr.append(fName).append(": ").append(s).append(", ");
                    }
                    sb.append(stringArrayStr);
                }
            }
        }
        return sb.toString().substring(0, sb.toString().length() - 2);
    }

The line it fails on in the code is the following:

for (String s : (String[]) f.get(this)) {

Why does this pass locally and fail using mvn? Can anybody tell me what is incorrect about this line?

Just to clear up - the model class has 3 types of field - String, List and String array. The errored line occurs on String array entries.

A