public void inferLowercase() {
        if (userSpecified) {
            // ignore inferred changes if user specified something
            return;
        }
        // do not increase level
        if (level == Level.NONE) return;
        if (level == Level.CODEPOINT) return;

        level = Level.LOWERCASE;
    }
Change the current level to LOWERCASE as inferred
by other features' needs.  If the current level
was user specified it will not change; also this
will not increase the level.
config-model/src/main/java/com/yahoo/schema/document/NormalizeLevel.java