private static void serializeGeoPos(JsonGenerator generator, FieldBase field, Struct value, GeoPosType dataType) {
        fieldNameIfNotNull(generator, field);
        wrapIOException(() -> {
                generator.writeStartObject();
                generator.writeFieldName("lat");
                generator.writeRawValue(dataType.fmtLatitude(value));
                generator.writeFieldName("lng");
                generator.writeRawValue(dataType.fmtLongitude(value));
                generator.writeEndObject();
        });
    }
@author Steinar Knutsen
@author Vegard Sjonfjell
document/src/main/java/com/yahoo/document/json/JsonSerializationHelper.java