Changes

Moving element collection relation mapping to the appropriate class instead of making it half in RelationConfigurer and half in ElementCollectionRelationConfigurer
 (commit: 687ec72)

Moving polymorphic handler to their dedicated package for better code organization
 (commit: e7b074f)

Fixing table-per-class polymorphism as root: case with multiple sub-classes wasn't supported
 (commit: e015e04)

Fixing table-per-class polymorphism as root: loading sub-persisters relations
 (commit: d3ec77e)

Fixing single-table polymorphism as root: loading sub-persisters relations
 (commit: 38c1b7a)

Adding log traces for better debugging
 (commit: f656e29)

Fixing join-table polymorphism as root: case with multiple sub-classes wasn't supported.
Required a lot of changes because joins configured by builder weren't correct (tree wasn't taking into account several sub-classes nor their relations). Which makes fail the selector, which, thus, was replaced by JoinTablePolymorphismEntityFinder for loading entities per their ids, which didn't support Composited Keys.
Addionally, sub-persisters listeners weren't triggered anymore (because the 2-phases load wasn't used anymore). So we make them trigger them again. Which makes appear some errors on ordered Collections (for example, the algorithm wasn't working on Set because we were trying to add the sorted elements to the already-filled Set, which was doing nothing since elements were already in the Set).
Finally, JoinTablePolymorphismSelectExecutor can be deleted because it has been replaced by JoinTablePolymorphismEntityFinder
 (commit: 639b575)

Applying the behavior of join-table polymorphism to tabler-per-class: selector is replaced by TablePerClassPolymorphismEntityFinder for loading entities per their ids.
TablePerClassPolymorphicSelectExecutor can be deleted.
 (commit: ecdc0e8)

Applying the behavior of join-table and table-per-class polymorphism to single-table: selector is replaced by SingleTablePolymorphismEntityFinder for loading entities per their ids.
SingleTablePolymorphismSelectExecutor can be deleted.
 (commit: f30d178)

Sharing doSelect(..) code between polymorphic persisters
 (commit: f6307b7)

Moving Select Listener propagation of polymorphic persister to sub-persister to avoid code duplication.
 (commit: 9be5d2e)