### 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
"type": "keyword",
                        "ignore_above": 256
                      }
                    }
                  }
                }
              }
            }"""), Strings.toString(doc.dynamicMappingsUpdate().getRoot()));
        merge(mapperService, dynamicMapping(doc.dynamicMappingsUpdate()));
        Mapping merged = mapperService.documentMapper().mapping();
        assertNotNull(merged.getRoot().getMapper("test"));
        assertEquals(1, merged.getRoot().runtimeFields().size());
        assertNotNull(merged.getRoot().getRuntimeField("field"));
    }
    public void testDynamicUpdateWithRuntimeFieldDottedName() throws Exception {
        MapperService mapperService = createMapperService(
            runtimeMapping(b -> b.startObject("path1.path2.path3.field").field("type", "keyword").endObject())
        );
        ParsedDocument doc = mapperService.documentMapper().parse(source(b -> {
            b.startObject("path1").startObject("path2").startObject("path3");
            b.field("field", "value");
            b.endObject().endObject().endObject();
        }));
        RootObjectMapper root = doc.dynamicMappingsUpdate().getRoot();
        assertEquals(0, root.runtimeFields().size());
        {
            
            Mapper path1 = root.getMapper("path1");
            assertThat(path1, instanceOf(ObjectMapper.class));
            Mapper path2 = ((ObjectMapper) path1).getMapper("path2");