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JPA Reference 3.2
CoreQueriesModelTuningAnnotations
ComponentsNamed QueriesFetch GraphsAttributesRelationshipsValue GenerationListeners & CallbacksContainer InjectionMapping (ORM)
AssociationOverrideAssociationOverridesAttributeOverrideAttributeOverridesCheckConstraintCollectionTableColumnConstraintModeDiscriminatorColumnDiscriminatorTypeDiscriminatorValueForeignKeyInheritanceInheritanceTypeJoinColumnJoinColumnsJoinTableIndexLobMapKeyClassMapKeyColumnMapKeyJoinColumnMapKeyJoinColumnsMapsIdOrderColumnPrimaryKeyJoinColumnPrimaryKeyJoinColumnsSecondaryTableSecondaryTablesTableUniqueConstraint
SQL Queries
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Jakarta Persistence (JPA) Method
in jakarta.persistence.MapKeyJoinColumn

boolean nullable()

(Optional) Whether the foreign key column is nullable.
Since:
Jakarta Persistence (JPA) 1.0
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Copyright © 2003, 2010,  2026  ObjectDB Software, all rights reserved. The JPA API Reference Documentation (JavaDoc) on this website is derived with some adjustments from the open source JPA 2 RI (EclipseLink) and is available under the terms of the Eclipse Public License, v. 1.0 and Eclipse Distribution License, v. 1.0. The JDO API Reference Documentation (JavaDoc) on this website is derived with some adjustments from the JDO 2.2 API and is available under the terms of the Apache License, v. 2.0. Images on this website are available under these licecnes. Documentation on this website explains how to use JPA in the context of the ObjectDB Object Database but mostly relevant also for ORM JPA implementations, such as Hibernate (and HQL), EclipseLink, TopLink, OpenJPA and DataNucleus. ObjectDB is not an ORM JPA implementation but an Object Database (ODBMS) for Java with built in JPA 2 support.