### 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
}));
        assertNotNull(doc.dynamicMappingsUpdate());
        merge(mapperService, dynamicMapping(doc.dynamicMappingsUpdate()));
        assertThat(mapperService.fieldType("s_long").typeName(), equalTo("long"));
        assertThat(mapperService.fieldType("s_double").typeName(), equalTo("double"));
    }
    public void testNumericDetectionDefault() throws Exception {
        MapperService mapperService = createMapperService(mapping(b -> {}));
        ParsedDocument doc = mapperService.documentMapper().parse(source(b -> {
            b.field("s_long", "100");
            b.field("s_double", "100.0");
        }));
        assertNotNull(doc.dynamicMappingsUpdate());
        merge(mapperService, dynamicMapping(doc.dynamicMappingsUpdate()));
        Mapper mapper = mapperService.documentMapper().mappers().getMapper("s_long");
        assertThat(mapper, instanceOf(TextFieldMapper.class));
        mapper = mapperService.documentMapper().mappers().getMapper("s_double");
        assertThat(mapper, instanceOf(TextFieldMapper.class));
    }
    public void testNumericDetectionDefaultDynamicRuntime() throws Exception {
        MapperService mapperService = createMapperService(dynamicMapping("runtime", b -> {}));
        ParsedDocument doc = mapperService.documentMapper().parse(source(b -> {
            b.field("s_long", "100");
            b.field("s_double", "100.0");
        }));
        assertNotNull(doc.dynamicMappingsUpdate());
        merge(mapperService, dynamicMapping(doc.dynamicMappingsUpdate()));
        assertThat(mapperService.fieldType("s_long").typeName(), equalTo("keyword"));
        assertThat(mapperService.fieldType("s_double").typeName(), equalTo("keyword"));
    }