Xtext validation Popup appears when defining a Program using DSL

[christophe-w]

A "Problem Occured" popup is shown when defining a Porgram in the DSL editor.
This Popup appears when the cursor is in the (empty) name part of:

• InputCondition
• Link
• Procedure
• OutputCondition

It's difficult to use the editor because of this Popup..

The stack trace of the error:
org.eclipse.emf.common.util.WrappedException: java.lang.IllegalArgumentException: Qualified name cannot be empty
at org.eclipse.xtext.linking.lazy.LazyLinkingResource.getEObject(LazyLinkingResource.java:201)
at org.eclipse.xtext.linking.lazy.LazyLinkingResource.resolveLazyCrossReference(LazyLinkingResource.java:139)
at org.eclipse.xtext.linking.lazy.LazyLinkingResource.resolveLazyCrossReferences(LazyLinkingResource.java:103)
at org.eclipse.xtext.EcoreUtil2.resolveLazyCrossReferences(EcoreUtil2.java:417)
at org.eclipse.xtext.validation.ResourceValidatorImpl.resolveProxies(ResourceValidatorImpl.java:127)
at org.eclipse.xtext.validation.ResourceValidatorImpl.validate(ResourceValidatorImpl.java:62)
at org.eclipse.xtext.ui.editor.validation.ValidationJob$1.exec(ValidationJob.java:79)
at org.eclipse.xtext.ui.editor.validation.ValidationJob$1.exec(ValidationJob.java:1)
at org.eclipse.xtext.util.concurrent.AbstractReadWriteAcces.readOnly(AbstractReadWriteAcces.java:32)
at org.eclipse.xtext.ui.editor.model.XtextDocument.readOnly(XtextDocument.java:86)
at org.eclipse.xtext.ui.editor.validation.ValidationJob.createIssues(ValidationJob.java:75)
at org.eclipse.xtext.ui.editor.validation.ValidationJob.run(ValidationJob.java:64)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)
Caused by: java.lang.IllegalArgumentException: Qualified name cannot be empty
at org.eclipse.xtext.naming.IQualifiedNameConverter$DefaultImpl.toQualifiedName(IQualifiedNameConverter.java:65)
at org.eclipse.xtext.naming.SimpleNameProvider.getFullyQualifiedName(SimpleNameProvider.java:28)
at org.eclipse.xtext.naming.IQualifiedNameProvider$AbstractImpl.apply(IQualifiedNameProvider.java:31)
at org.eclipse.xtext.naming.IQualifiedNameProvider$AbstractImpl.apply(IQualifiedNameProvider.java:1)
at org.eclipse.xtext.scoping.Scopes$2.apply(Scopes.java:90)
at org.eclipse.xtext.scoping.Scopes$2.apply(Scopes.java:1)
at com.google.common.collect.Iterators$8.next(Iterators.java:697)
at com.google.common.collect.Iterators$7.computeNext(Iterators.java:602)
at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:135)
at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:130)
at org.eclipse.xtext.scoping.impl.MultimapBasedSelectable.setExportedObjects(MultimapBasedSelectable.java:97)
at org.eclipse.xtext.scoping.impl.MultimapBasedSelectable.(MultimapBasedSelectable.java:36)
at org.eclipse.xtext.scoping.impl.SimpleLocalScopeProvider.getAllDescriptions(SimpleLocalScopeProvider.java:75)
at org.eclipse.xtext.scoping.impl.SimpleLocalScopeProvider$1.get(SimpleLocalScopeProvider.java:57)
at org.eclipse.xtext.scoping.impl.SimpleLocalScopeProvider$1.get(SimpleLocalScopeProvider.java:1)
at org.eclipse.xtext.util.OnChangeEvictingCache.get(OnChangeEvictingCache.java:46)
at org.eclipse.xtext.scoping.impl.SimpleLocalScopeProvider.getScope(SimpleLocalScopeProvider.java:54)
at org.eclipse.xtext.scoping.impl.AbstractDeclarativeScopeProvider.delegateGetScope(AbstractDeclarativeScopeProvider.java:72)
at org.eclipse.xtext.scoping.impl.AbstractDeclarativeScopeProvider.getScope(AbstractDeclarativeScopeProvider.java:102)
at org.eclipse.xtext.linking.impl.DefaultLinkingService.getScope(DefaultLinkingService.java:59)
at org.eclipse.xtext.linking.impl.DefaultLinkingService.getLinkedObjects(DefaultLinkingService.java:119)
at org.eclipse.xtext.linking.lazy.LazyLinkingResource.getEObject(LazyLinkingResource.java:170)
... 12 more