### 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/test/java/org/elasticsearch/index/mapper/DynamicMappingTests.java
{
              "time" : 10,
              "time.max" : 500,
              "time.min" : 1,
              "host.name" : "localhost",
              "host.id" : 111
            }
            """));
        Mapping mappingsUpdate = doc.dynamicMappingsUpdate();
        assertNotNull(mappingsUpdate);
        assertNotNull(mappingsUpdate.getRoot().getMapper("time"));
        assertNotNull(mappingsUpdate.getRoot().getMapper("time.max"));
        assertNotNull(mappingsUpdate.getRoot().getMapper("time.min"));
        assertNotNull(mappingsUpdate.getRoot().getMapper("host.id"));
        assertNull(mappingsUpdate.getRoot().getMapper("host.name"));
        assertNotNull(doc.rootDoc().getFields("time"));
        assertNotNull(doc.rootDoc().getFields("time.max"));
        assertNotNull(doc.rootDoc().getFields("time.min"));
        assertNotNull(doc.rootDoc().getFields("host.name"));
        assertNotNull(doc.rootDoc().getFields("host.id"));
        merge(mapperService, dynamicMapping(mappingsUpdate));
        assertNotNull(mapperService.fieldType("time"));
        assertNotNull(mapperService.fieldType("time.max"));
        assertNotNull(mapperService.fieldType("time.min"));
        assertNotNull(mapperService.fieldType("host.id"));
        assertNotNull(mapperService.fieldType("host.name"));
        assertEquals(0, mapperService.mappingLookup().objectMappers().size());
    }
}