Wrapping PersistentSet of one-to-many relationship throws error during Annotation based mapping where as no error is thrown in xml based mapping

Hibernate ORM
1

In our codebase, we use xml file for mapping entities to tables. This was created back in 2010.
Eventually for some of our one-to-many relationship b/w entities we introduced a wrapper over PersistentSet.

One such instance where two entities, ConfigContainer.java and Config.java are related by one-to-many association:

  <class name="org.namespace.ConfigContainer"
         table="CONFIG_CONTAINERS">

    <id name="id" column="CONFIG_CONTAINER_ID">
      <generator class="native"/>
    </id>
    <version name="optimisticLockVersion"
             column="OPTIMISTIC_LOCK_VERSION"
             type="long"/>
    <property name="configType" column="CONFIG_TYPE" not-null="true" unique="true"/>

    <!-- Configs are saved via cascade but are deleted explicitly. -->
    <set name="configsForDb" inverse="true" cascade="save-update,merge,persist">
      <key column="CONFIG_CONTAINER_ID"/>
      <one-to-many class="org.namespace.Config"/>
    </set>

    <property name="configGeneration" column="CONFIG_GENERATION" not-null="true"/>
  </class>


    <class name="DbConfig" table="CONFIGS">
    <id name="id" column="CONFIG_ID">
      <generator class="native"/>
    </id>

    <version column="OPTIMISTIC_LOCK_VERSION" name="optimisticLockVersion" type="long" />

    <many-to-one name="configContainer"
                 column="CONFIG_CONTAINER_ID"
                 class="org.namespace.DbConfigContainer"
                 foreign-key="FK_CONFIG_CONFIG_CONTAINER"
                 index="IDX_CONFIG_CONFIG_CONTAINER"/>
  </class>

POJO for ConfigContainer.java is :

public class ConfigContainer  {

  private Wrapper<Config> configs = new Wrapper<Config>(Sets.<DbConfig> newHashSet());

    /**
   * Hibernate uses this to pass in a PersistentSet object (which
   * loads things lazily.  We wrap it a bit, but make sure to give
   * back the original object, too.
   */
  public void setConfigsForDb(Set<Config> configs) {
    this.configs = new Wrapper<Config>(configs);
  }

  public Set<DbConfig> getConfigsForDb() {
    return configs.delegate();
  }

}

The above Wrapper.java is basically a cache which stores the configs. I can more info if you want.

We are currently facing Performance issues 1.

We want to ask the above problem in this community again. So we are first creating a dummy project modelling such entities. But this time we are using Annotations instead of xml for mapping.

Here is ConfigContainer.java in our dummy project using Annotations.

@Entity
@Table(name = "CONFIG_CONTAINERS")
public class ConfigContainer {

	@OneToMany(cascade=CascadeType.ALL, mappedBy="configContainer")
	private Wrapper<DbConfig> configs =
			new Wrapper<>(new HashSet<DbConfig>());

	public void setConfigsForDb(Set<Config> configs) {
		this.configs = new Wrapper<>(configs);
	}

	public Set<Config> getConfigsForDb() {
		return configType.delegate;
	}  
}

But when I run the code, the following exceptions were thrown:

org.namespace.Wrapper collection type not supported for property: org.namespace.ConfigContainer.configs

Custom type does not implement UserCollectionType: org.namespace.Wrapper

I know the solution is to make the Wrapper.java implement UserCollectionType 2

My question is, why I am not getting the same error in my actual codebase ? In actual codebase, the Wrapper.java class doesn’t implement UserCollectionType. Also I have grep-ed my entire codebase but didn’t find any usages of UserCollectionType. How is it working in xml based mapping.

Hibernate-version: 5.4.27.Final

2

You have to annotate the getter getConfigsForDb with @OneToMany to get the same configuration.

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