### Description

Dynamic mappings can greatly help the getting started experience but they currently don't apply to all types, one example is `dense_vector`.

It's been suggested to automatically map float arrays as dense vectors when there are more than 100 values, or a heuristic along these lines.
server/src/main/java/org/elasticsearch/index/mapper/DocumentParser.java
if (docsReversed) {
                throw new IllegalStateException("documents are already reversed");
            }
            return documents.subList(1, documents.size());
        }
        /**
         * Returns a copy of the provided {@link List} where parent documents appear
         * after their children.
         */
        private List<LuceneDocument> reorderParentAndGetDocs() {
            if (documents.size() > 1 && docsReversed == false) {
                docsReversed = true;
                
                List<LuceneDocument> newDocs = new ArrayList<>(documents.size());
                LinkedList<LuceneDocument> parents = new LinkedList<>();
                for (LuceneDocument doc : documents) {
                    while (parents.peek() != doc.getParent()) {
                        newDocs.add(parents.poll());
                    }
                    parents.add(0, doc);
                }
                newDocs.addAll(parents);
                documents.clear();
                documents.addAll(newDocs);
            }
            return documents;
        }
    }
}