private Object getCheckType(String fieldName, Schema.Type type) {
        Field field = lookupField(fieldName);
        if (field.schema().type() != type)
            throw new DataException("Field '" + fieldName + "' is not of type " + type);
        return values[field.index()];
    }
Validates that this struct has filled in all the necessary data with valid values. For required fields
without defaults, this validates that a value has been set and has matching types/schemas. If any validation
fails, throws a {@link DataException}.
connect/api/src/main/java/org/apache/kafka/connect/data/Struct.java