#vulnerable code 
                             Object fromDb(DBObject dbObject, final Object entity, EntityCache cache) {
		// check the history key (a key is the namespace + id)
		
		if (dbObject.containsField(ID_KEY) && getMappedClass(entity).getIdField() != null
				&& getMappedClass(entity).getEntityAnnotation() != null) {
			Key key = new Key(entity.getClass(), dbObject.get(ID_KEY));
			Object cachedInstance = cache.getEntity(key);
			if (cachedInstance != null)
				return cachedInstance;
			else
				cache.putEntity(key, entity); // to avoid stackOverflow in recursive refs
		}
		
		//hack to bypass things and just read the value.
		if (entity instanceof MappedField) {
			readMappedField(dbObject, (MappedField) entity, entity, cache);
			return entity;
		}
		
		MappedClass mc = getMappedClass(entity);
		
		dbObject = (BasicDBObject) mc.callLifecycleMethods(PreLoad.class, entity, dbObject, this);
		try {
			for (MappedField mf : mc.getPersistenceFields()) {
				readMappedField(dbObject, mf, entity, cache);
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		}

		if (dbObject.containsField(ID_KEY) && getMappedClass(entity).getIdField() != null) {
			Key key = new Key(entity.getClass(), dbObject.get(ID_KEY));
			cache.putEntity(key, entity);
		}
		mc.callLifecycleMethods(PostLoad.class, entity, dbObject, this);
		return entity;
	} 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             Object fromDb(DBObject dbObject, final Object entity, EntityCache cache) {
		//hack to bypass things and just read the value.
		if (entity instanceof MappedField) {
			readMappedField(dbObject, (MappedField) entity, entity, cache);
			return entity;
		}
		
		// check the history key (a key is the namespace + id)
		
		if (dbObject.containsField(ID_KEY) && getMappedClass(entity).getIdField() != null
				&& getMappedClass(entity).getEntityAnnotation() != null) {
			Key key = new Key(entity.getClass(), dbObject.get(ID_KEY));
			Object cachedInstance = cache.getEntity(key);
			if (cachedInstance != null)
				return cachedInstance;
			else
				cache.putEntity(key, entity); // to avoid stackOverflow in recursive refs
		}
		
		MappedClass mc = getMappedClass(entity);
		
		dbObject = (BasicDBObject) mc.callLifecycleMethods(PreLoad.class, entity, dbObject, this);
		try {
			for (MappedField mf : mc.getPersistenceFields()) {
				readMappedField(dbObject, mf, entity, cache);
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		}

		if (dbObject.containsField(ID_KEY) && getMappedClass(entity).getIdField() != null) {
			Key key = new Key(entity.getClass(), dbObject.get(ID_KEY));
			cache.putEntity(key, entity);
		}
		mc.callLifecycleMethods(PostLoad.class, entity, dbObject, this);
		return entity;
	}