public boolean existsIndex(String name) {
        if (indices.get(name) != null)
            return true;
        if (inherited.isPresent() && requireInherited().existsIndex(name))
            return true;
        for (ImmutableSDField field : allConcreteFields()) {
            if (field.existsIndex(name))
                return true;
        }
        return false;
    }
Returns the schema level index of this name, in this or any inherited schema, if any
config-model/src/main/java/com/yahoo/schema/Schema.java