A quick search on the net reveals 3 or 4 variants how folks have been specifying xmlns and xsi:schemaLocation in persistence.xml.
What would be the 'correct' manner to specify JPA version 2.1?
I'm using:
<persistence version="2.1"
xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
Andrei I
According to the official documentation it must be (like yours):
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
...
</persistence>
来源：https://stackoverflow.com/questions/21142168/how-to-specify-jpa-2-1-in-persistence-xml