plugins/mapper-murmur3/src/main/java/org/elasticsearch/index/mapper/murmur3/Murmur3FieldMapper.java
private Murmur3FieldType(String name, boolean isStored, Map<String, String> meta) {
            super(name, false, isStored, true, TextSearchInfo.NONE, meta);
        }
        @Override
        public String typeName() {
            return CONTENT_TYPE;
        }
        @Override
        public IndexFieldData.Builder fielddataBuilder(FieldDataContext fieldDataContext) {
            failIfNoDocValues();
            return new SortedNumericIndexFieldData.Builder(name(), NumericType.LONG, Murmur3DocValueField::new);
        }
        @Override
        public ValueFetcher valueFetcher(SearchExecutionContext context, String format) {
            return SourceValueFetcher.toString(name(), context, format);
        }