@Override
    public Manager<ENTITY> build() {
        requireNonNull(strategy, getClass().getSimpleName() +
            ".withParallelStrategy(...) has not been called!"
        );

        return new ConfiguredManager<>(streams, manager, strategy);
    }
Default implementation of {@link ManagerConfigurator} that allows a new
default {@link ParallelStrategy} to be set in the delegating {@link Manager}.

@param <ENTITY> Entity type

@author Per Minborg
@since  3.0.1
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/internal/manager/ManagerConfiguratorImpl.java