Mapping problem with tablePerSubclass if parent is abstract class

# Problem

Table Per subclass not working if parent is abstract class
# Scenario

I have created following hierarchy of domain classes

Grails 3.0.10
JVM 1.7

abstract class Image(){
String name
String path
mapping:{
tablePerHierarchy false
id column: "image_id"
}
}

class userImage extends Image(){
User user
static belongsTo:[User]
mapping:{
id column: "image_id"
}
}

class itemImage extends Image(){
Item item
static belongsTo:[Item]
mapping:{
id column: "image_id"
}
}

class User(){
String name
static hasMany:[images:UserImage]
}

class Item(){
String name
static hasMany:[images:ItemImage]
}

Bootstrap.groovy

Item itm = new Item()
itm.name = "item name"

ItemImage img = new ItemImage()
img.name = "img name"
img.path = "dummy path"

itm.addToImages(img)

itm.save(flush:true)

// successfully saved the record in 3 tables
item
item_mage
image

def newItem = item.get(itm.id) // pass newly created id
def images = item.images

ERROR : column image_0.class not found.
#

If i try to define images as type of Image it gives problem at insert, as follows
- It restricts me to define itemImages id key as column "item_image_id"
- It try to insert into item_image twice
- When I look in to table I found there are two foreign keys created one as image and another for images

Start by reproducing the hierarchy in Grails 3.0.10 with an abstract Image parent and table-per-subclass mappings. Inspect the generated item, item_image, and image tables and the query for item.images, then compare the behavior when associations use Image versus ItemImage. Done means loading the association succeeds without the missing image_0.class column or duplicate inserts and foreign keys.

Written by the indexing model from the issue text.