Guiced Persistence gives you JTA with multi-datasource connection, and distributed connection handling through BTM.
This project exposes a Module DatabaseModule that you can extend to configure and connect your databases as you desire 
<dependency>
    <groupId>com.guicedee.persistence</groupId>
    <artifactId>guiced-persistence</artifactId>
</dependency>

You will need an annotation to identify the connection 
@Qualifier
@Target({ METHOD,FIELD,PARAMTER })
@Retention(RetentionPolicy.RUNTIME)
@BindingAnnotation
public @interface MyDB {
}
Mark the requirement, and register your new module with the IGuiceModule service 
module my.module {
    requires com.guicedee.guicedpersistence;
    provides IGuiceModule with DBModule;
}
A database module is needed to configure the connection, with overridable properties to alter it in any way 
public class DBModule extends DatabaseModule<DBModule>
{
    protected @NotNull String getPersistenceUnitName()
    {
        return "MyFirstPersistenceUnit";
    }
    protected @NotNull ConnectionBaseInfo getConnectionBaseInfo(PersistenceUnit unit, Properties filteredProperties)
    {
        return new BTMConnectionBaseInfo();
    }
    protected @NotNull String getJndiMapping()
    {
        return "jndi/jta/datasource";
    }
    protected @NotNull Class<? extends Annotation> getBindingAnnotation()
    {
        return MyDb.class;
    }
}
Method Interception can specify which transaction to start on which database source. A Request Scoper is available to make each request into it's own unit of work for complete transaction control 
@Transactional(entityManagerAnnotation = MyDb.class,timeout = 500)
public void me();
The request scoping addon can be added on by simply including the artifact, and adding it to your module-info file 
<dependency>
    <groupId>com.guicedee.servlets</groupId>
    <artifactId>guiced-servlets-request-scoper</artifactId>
</dependency>

Currently you can use the following ConnectionBaseInfo types (or your own)

  • BTMConnectionBaseInfo (JTA)
  • JPAConnectionBaseInfo (Non-Pooled JPA)
  • C3P0ConnectionBaseInfo (For Pooled JPA)
  • WildflyConnectionBaseInfo (For standalone files)

This module will bind (and log) the following bindings with the annotation as a key, 
EntityManagerFactory.class
EntityManager.class
PersistService.class
UnitOfWork.class
PersistenceUnit.class
DataSource.class