isId() - JPA SingularAttribute's method

Is the attribute an id attribute. This method will return true if the attribute is an attribute that corresponds to a simple id, an embedded id, or an attribute of an id class.
boolean indicating whether the attribute is an id
JPA 2.0

This documentation page 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.
Object Relational Mapping (ORM) JPA 2 providers include Hibernate, EclipseLink, TopLink, OpenJPA and DataNucleus.
ObjectDB is not an ORM JPA implementation but an Object Database for Java with built in JPA 2 support.