interface Datastore {
     ...
  

        /** updates all entities found with the operations*/
        <T> UpdateResults<T> update(Query<T> query, UpdateOperations<T> ops);
        /** updates all entities found with the operations; if nothing is found insert the update as an entity if "createIfMissing" is true*/
        <T> UpdateResults<T> update(Query<T> query, UpdateOperations<T> ops, boolean createIfMissing);
        /** updates the first entity found with the operations*/
        <T> UpdateResults<T> updateFirst(Query<T> query, UpdateOperations<T> ops);
        /** updates the first entity found with the operations; if nothing is found insert the update as an entity if "createIfMissing" is true*/
        <T> UpdateResults<T> updateFirst(Query<T> query, UpdateOperations<T> ops, boolean createIfMissing);
        /** updates the first entity found with the operations; if nothing is found insert the update as an entity if "createIfMissing" is true*/
        <T> UpdateResults<T> updateFirst(Query<T> query, T entity, boolean createIfMissing);
}
public interface UpdateOperations<T> {
        /** sets the field value */
        UpdateOperations<T> set(String fieldExpr, Object value);
        /** removes the field */
        UpdateOperations<T> unset(String fieldExpr);


        /** adds the value to an array field*/
        UpdateOperations<T> add(String fieldExpr, Object value);
        UpdateOperations<T> add(String fieldExpr, Object value, boolean addDups);
        /** adds the values to an array field*/
        UpdateOperations<T> addAll(String fieldExpr, List<?> values, boolean addDups);
        
        /** removes the first value from the array*/
        UpdateOperations<T> removeFirst(String fieldExpr);
        /** removes the last value from the array*/
        UpdateOperations<T> removeLast(String fieldExpr);
        /** removes the value from the array field*/
        UpdateOperations<T> removeAll(String fieldExpr, Object value);
        /** removes the values from the array field*/
        UpdateOperations<T> removeAll(String fieldExpr, List<?> values);


        /** decrements the numeric field by 1*/
        UpdateOperations<T> dec(String fieldExpr);
        /** increments the numeric field by 1*/
        UpdateOperations<T> inc(String fieldExpr);
        /** increments the numeric field by value (negatives are allowed)*/
        UpdateOperations<T> inc(String fieldExpr, Number value);
}