Allow single Object fields to accept any type in acceptChange (#19)

* allow single Object fields to accept any type in acceptChange

* move Object check under the existing isAnyFieldSingle check

Author: miberss

src/main/java/com/sovdee/oopsk/elements/expressions/ExprFieldAccess.java

@@ -184,6 +184,11 @@ protected Object[] get(Event event, Struct[] source) {
 
         // if we have a single field, we can delegate to that type's changer, so get all the classes from the changers
         if (isAnyFieldSingle) {
+            // if a field is single and object, it should accept all changers
+            if (returnType == Object.class) {
+                return new Class<?>[]{Object.class};
+            }
+
             Set<Class<?>> distinctClasses = Arrays.stream(returnTypes)
                     .map(Classes::getSuperClassInfo)
                     .filter(Objects::nonNull)