Map<String, Object> updateInfo; // Key is db column name, value is updatedValue

Then create update operations:

Query<Entity> filter = datastore.createQuery(Entity.class)
                                .field("_id", id);

UpdateOperations<Entity> updateOps = datastore.createUpdateOperations(Entity.class);

updateInfo.entrySet().forEach(e -> updateOps.set(e.getKey(), e.getValue());

datastore.update(filter, updateOps);