Persistence.generateSchema - the output file contains duplicated DDL statements

Hi,

I am using the JPA2.1 API: Persistence.generateSchema(persistentUnit, properties) with Hibernate 4.3,5.0,5.1.

My code: https://github.com/lorislab/jpa2-maven-plugin/blob/master/src/main/java/org/lorislab/maven/jpa2/SchemaGeneratorMojo.java

Hibernate 4.3.x, 5.0.x generated the DDL-script fine (without semicolon).
Hibernate 5.1 and Persistence.generateSchema generated the DDL-script with semicolon but the output file contains two same DDL-scripts.
Example:
Create Table TABLE1
Create Index INDEX1
Create Table TABLE1
Create Index INDEX1

I think it’s because of the code in the EntityManagerFactoryBuilderImpl and SessionFactoryImpl.

Class: org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.generateSchema

try {
SessionFactoryBuilder sfBuilder = metadata().getSessionFactoryBuilder();
populate( sfBuilder, standardServiceRegistry );
sfBuilder.build();

SchemaManagementToolCoordinator.process(
metadata, standardServiceRegistry, configurationValues, DelayedDropRegistryNotAvailableImpl.INSTANCE
);
}

The line sfBuilder.build(); call the org.hibernate.internal.SessionFactoryImpl constructor.
Line 458 of the SessionFactoryImpl constructor:

SchemaManagementToolCoordinator.process(
metadata,
serviceRegistry,
properties,
new DelayedDropRegistry() {
@Override
public void registerOnCloseAction(DelayedDropAction action) {
SessionFactoryImpl.this.delayedDropAction = action;
}
}
);

Commit: https://github.com/hibernate/hibernate-orm/commit/17de173cb5334d866f1886d3e057f49a6c987bad