Avoid casting struct to Hashmap

[PierreZ]

In RecordLayer.java:

        .map(dynamicMessage -> {
          Map<String, Object> results = new HashMap<>();
          dynamicMessage.getAllFields().forEach((key, value) -> results.put(key.getName(), value));
          return results;

We are doing this because:

Once we have a list of ProductDTO objects we typically don’t need specialised data fetchers on each field. graphql-java ships with a smart graphql.schema.PropertyDataFetcher that knows how to follow POJO patterns based on the field name. In the example above there is a name field and hence it will try to look for a public String getName() POJO method to get the data.

https://www.graphql-java.com/documentation/v11/data-fetching/