Implementation of EntityPart API

[jansupol]

Signed-off-by: jansupol [email protected]

[jbescos]

You can get rid of both variables with an inner static class. The good advantage is that there is no need for volatile and to have a lock.

private static class Lazy {

    private static final EntityPartBuilderProvider cachedEntityPartBuilderProvider = findEntityPartBuilderProvider();

    /**
     * Obtain a {@code RuntimeDelegate} instance using the method described in {@link #getInstance}.
     *
     * @return an instance of {@code RuntimeDelegate}.
     */
    private static EntityPartBuilderProvider findEntityPartBuilderProvider() {
        for (final EntityPartBuilderProvider entityPartBuilder : ServiceFinder.find(EntityPartBuilderProvider.class)) {
            if (entityPartBuilder != null) {
                return entityPartBuilder;
            }
        }
        throw new IllegalArgumentException(LocalizationMessages.NO_ENTITYPART_BUILDER_FOUND());
    }
}

And later get the instance in this way. It will be loaded the first time is used.
Lazy.cachedEntityPartBuilderProvider

[jansupol]

We may utilize Jersey LazyValue for this