Exception in DescriptorBuilder when inherited properties have the same name

Hi,

the DescriptorBuilder throws an exception if a property with the same name is defined in the inheritance chain of more than one of its super classes:

Error: property <any> already defined; override of <mh:AnotherRoot#mh:any> by <props:Root#props:any> not allowed without redefines
      at DescriptorBuilder._fd7‍.r.DescriptorBuilder.assertNotDefined (lib/descriptor-builder.js:180:11)
      at DescriptorBuilder._fd7‍.r.DescriptorBuilder.addNamedProperty (lib/descriptor-builder.js:138:10)
      at DescriptorBuilder._fd7‍.r.DescriptorBuilder.addProperty (lib/descriptor-builder.js:53:8)
      at DescriptorBuilder.<anonymous> (lib/descriptor-builder.js:227:12)
      at forEach (node_modules/min-dash/dist/index.js:170:20)
      at DescriptorBuilder._fd7‍.r.DescriptorBuilder.addTrait (lib/descriptor-builder.js:202:3)
      at lib/registry.js:185:13
      at Registry._0ac‍.r.Registry.mapTypes (lib/registry.js:165:3)
      at traverseSuper (lib/registry.js:155:10)
      at forEach (node_modules/min-dash/dist/index.js:170:20)
      at Registry._0ac‍.r.Registry.mapTypes (lib/registry.js:162:3)
      at Registry._0ac‍.r.Registry.getEffectiveDescriptor (lib/registry.js:184:8)
      at Moddle._1b8‍.r.Moddle.getType (lib/moddle.js:97:32)
      at Moddle._1b8‍.r.Moddle.create (lib/moddle.js:65:19)
      at Context.<anonymous> (test/spec/properties.js:589:34)
      at processImmediate (internal/timers.js:461:21)

I created a test case with a simplified hierarchy:

mh:MultipleInherited has two properties named any:

• mh:AnotherRoot#any
• props:Root#any

and the DescriptorBuilder does not map them into seperate namespaces.

In my use-case, the problem occurs with the UMLDI meta-model, where all the diagram types inherit from UMLDI:UMLDiagram:

Regards,
Frank

Start with the reproducer linked in commit b1b9795512d67f3bab3e7135068ad52f8c552f1d and test/spec/properties.js around the reported failure at line 589. Read lib/descriptor-builder.js, especially addProperty, addNamedProperty, assertNotDefined, and addTrait, along with the inheritance traversal in lib/registry.js. Done means the MultipleInherited hierarchy no longer throws when inherited properties share a name and both properties are mapped into separate namespaces.