### 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
import org.elasticsearch.common.regex.Regex;
import org.elasticsearch.common.xcontent.XContentHelper;
import org.elasticsearch.index.IndexVersion;
import org.elasticsearch.index.fielddata.FieldDataContext;
import org.elasticsearch.index.fielddata.IndexFieldDataCache;
import org.elasticsearch.index.query.SearchExecutionContext;
import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
import org.elasticsearch.plugins.internal.DocumentParsingObserver;
import org.elasticsearch.search.lookup.SearchLookup;
import org.elasticsearch.search.lookup.Source;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentLocation;
import org.elasticsearch.xcontent.XContentParseException;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParserConfiguration;
import org.elasticsearch.xcontent.XContentType;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.function.Consumer;
import java.util.function.Supplier;
/**
 * A parser for documents
 */
public final class DocumentParser {