@Override
            protected Field<T> copy(IdStrategy strategy)
            {
                return createCollectionPojoV(number, name, f, messageFactory, 
                        0 != (strategy.flags & IdStrategy.PRESERVE_NULL_ELEMENTS),
                        genericType, strategy);
            }
For lazy initialization called by {@link RuntimeFieldFactory}.
protostuff-runtime/src/main/java/io/protostuff/runtime/RuntimeCollectionFieldFactory.java