private static void decode(Slime slime, String name, Inspector inspector, ConfigPayloadBuilder builder) {
            switch (inspector.type()) {
                case STRING -> builder.setField(name, inspector.asString());
                case LONG -> builder.setField(name, String.valueOf(inspector.asLong()));
                case DOUBLE -> builder.setField(name, String.valueOf(inspector.asDouble()));
                case BOOL -> builder.setField(name, String.valueOf(inspector.asBool()));
                case OBJECT -> decodeObject(slime, builder.getObject(name), inspector);
                case ARRAY -> decodeArray(slime, builder.getArray(name), inspector);
            }
        }
Try and verify that index mode is possible.
config/src/main/java/com/yahoo/vespa/config/ConfigPayloadBuilder.java