test/framework/src/main/java/org/elasticsearch/index/mapper/MapperTestCase.java
XContentBuilder mapping = fieldMapping(b -> {
            metaMapping(b);
            b.field("meta", Collections.singletonMap("foo", "bar"));
        });
        MapperService mapperService = createMapperService(mapping);
        assertEquals(
            XContentHelper.convertToMap(BytesReference.bytes(mapping), false, mapping.contentType()).v2(),
            XContentHelper.convertToMap(mapperService.documentMapper().mappingSource().uncompressed(), false, mapping.contentType()).v2()
        );
        mapping = fieldMapping(this::metaMapping);
        merge(mapperService, mapping);
        assertEquals(
            XContentHelper.convertToMap(BytesReference.bytes(mapping), false, mapping.contentType()).v2(),
            XContentHelper.convertToMap(mapperService.documentMapper().mappingSource().uncompressed(), false, mapping.contentType()).v2()
        );
        mapping = fieldMapping(b -> {
            metaMapping(b);
            b.field("meta", Collections.singletonMap("baz", "quux"));
        });
        merge(mapperService, mapping);
        assertEquals(
            XContentHelper.convertToMap(BytesReference.bytes(mapping), false, mapping.contentType()).v2(),
            XContentHelper.convertToMap(mapperService.documentMapper().mappingSource().uncompressed(), false, mapping.contentType()).v2()
        );
    }
    public final void testDeprecatedBoost() throws IOException {
        try {
            createMapperService(Version.V_7_10_0, fieldMapping(b -> {
                minimalMapping(b);
                b.field("boost", 2.0);