### 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/DocumentParserContext.java
public final void version(Field version) {
        this.version = version;
    }
    public final String id() {
        if (id == null) {
            assert false : "id field mapper has not set the id";
            throw new IllegalStateException("id field mapper has not set the id");
        }
        return id;
    }
    public final void id(String id) {
        this.id = id;
    }
    public final SeqNoFieldMapper.SequenceIDFields seqID() {
        return this.seqID;
    }
    public final void seqID(SeqNoFieldMapper.SequenceIDFields seqID) {
        this.seqID = seqID;
    }
    /**
     * Description on the document being parsed used in error messages. Not
     * called unless there is an error.
     */
    public final String documentDescription() {
        IdFieldMapper idMapper = (IdFieldMapper) getMetadataMapper(IdFieldMapper.NAME);
        return idMapper.documentDescription(this);
    }
    public Mapper getMapper(String name) {
        return parent.getMapper(name);
    }