public long [] getIndexes() {
        long[] asLong = new long[indexes.length];
        for (int i=0; i < indexes.length; i++) {
            asLong[i] = indexes[i];
        }
        return asLong;
    }
Retrieve the index that can be used for direct lookup in an indexed tensor.
vespajlib/src/main/java/com/yahoo/tensor/DirectIndexedAddress.java