private Location with(Object base, long offset, int length) {
            this.isDefined = true;
            this.memoryPage = null;
            keyLength = Platform.getInt(base, offset);
            valueLength = length - 4 - keyLength;
            keyMemoryLocation.setObjAndOffset(base, offset + 4);
            valueMemoryLocation.setObjAndOffset(base, offset + 4 + keyLength);
            return this;
        }
This is only used for spilling
indexr-query-opt/src/main/java/org/apache/spark/unsafe/map/BytesToBytesMap.java