public Object get(String fieldName) {
        Field field = lookupField(fieldName);
        return get(field);
    }
Get the value of a field, returning the default value if no value has been set yet and a default value is specified
in the field's schema. Because this handles fields of all types, the value is returned as an {@link Object} and
must be cast to a more specific type.
@param fieldName the field name to lookup
@return the value for the field
connect/api/src/main/java/org/apache/kafka/connect/data/Struct.java