private Map<Integer, Integer> getTypeIndexesPerLevel() {
        if (this.typeIndexesPerLevel == null) {
            this.typeIndexesPerLevel = new HashMap<Integer, Integer>(4);
        }
        return this.typeIndexesPerLevel;
    }
private Map < Integer , Integer > getTypeIndexesPerLevel ( ) { if ( this . typeIndexesPerLevel == null ) { this . typeIndexesPerLevel = new HashMap < Integer , Integer > ( 4 ) ; } return this . typeIndexesPerLevel ; }
Obtain the (lazily constructed) type-indexes-per-level Map.