java.lang.IllegalStateException: Internal error: Expected ca.gc.nrcan.mis_nap.data.Hierarchylevelname on stack, found java.util.Set

When I try to run the build-binding.xml file, I got this exception : java.lang.IllegalStateException: Internal error: Expected ca.gc.nrcan.mis_nap.data.Hierarchylevelname on stack, found java.util.Set.

Is this a binding error or a bug ??

<binding>

<mapping class="ca.gc.nrcan.mis_nap.data.MdMetadata" name="MD_Metadata">
<namespace uri="http://www.isotc211.org/2005/gmd" default="elements" prefix="gmd"/>
<structure map-as="ca.gc.nrcan.mis_nap.data.base.BaseMdMetadata"/>
</mapping>
<mapping class="ca.gc.nrcan.mis_nap.data.base.BaseMdMetadata" abstract="true">
[...]
<collection field="objHierarchylevelnameSet"
create-type="java.util.TreeSet"
item-type="ca.gc.nrcan.mis_nap.data.Hierarchylevelname">
<structure map-as="ca.gc.nrcan.mis_nap.data.Hierarchylevelname"/>
</collection>
</mapping>

<mapping class="ca.gc.nrcan.mis_nap.data.Hierarchylevelname" abstract="true">
<namespace uri="http://www.isotc211.org/2005/gmd" default="elements" prefix="gmd"/>
<structure map-as="ca.gc.nrcan.mis_nap.data.base.BaseHierarchylevelname"/>
</mapping>
<mapping class="ca.gc.nrcan.mis_nap.data.base.BaseHierarchylevelname" abstract="true">
<namespace uri="http://www.isotc211.org/2005/gmd" default="elements" prefix="md"/>
<value name="id" get-method="getId" set-method="setId" style="attribute" usage="optional"/>
<structure name="hierarchyLevelName" field="hierarchylevelname"
usage="required" type="java.lang.String"
marshaller="ca.gc.nrcan.marshalling.CharacterStringMapper"
unmarshaller="ca.gc.nrcan.marshalling.CharacterStringMapper"/>
<structure field="objMdMetadata" type="ca.gc.nrcan.mis_nap.data.MdMetadata"/>
</mapping>
</binding>

Running JiBX binding compiler
[bind] Error running binding compiler
[bind] *** Error during code generation for file 'E:\centreTopographique\installation\workspace\jibx-genbinding/binding.xml' - please enter a bug report for this error in Jira if the problem is not listed as fixed on the online status page ***
[bind] java.lang.IllegalStateException: Internal error: Expected ca.gc.nrcan.mis_nap.data.Hierarchylevelname on stack, found java.util.Set
[bind] full stack:
[bind] 0: java.util.Set
[bind] 1: java.util.Set
[bind] 2: org.jibx.runtime.impl.UnmarshallingContext
[bind] at org.jibx.binding.classes.MethodBuilder.verifyCompatible(MethodBuilder.java:420)
[bind] at org.jibx.binding.classes.MethodBuilder.verifyCallStack(MethodBuilder.java:537)
[bind] at org.jibx.binding.classes.MethodBuilder.appendCallVirtual(MethodBuilder.java:894)
[bind] at org.jibx.binding.def.ObjectBinding.genUnmarshalCall(ObjectBinding.java:579)
[bind] at org.jibx.binding.def.ObjectBinding.genUnmarshalContentCall(ObjectBinding.java:834)
[bind] at org.jibx.binding.def.ObjectBinding.genContentUnmarshal(ObjectBinding.java:943)
[bind] at org.jibx.binding.def.ComponentProperty.genContentUnmarshal(ComponentProperty.java:225)
[bind] at org.jibx.binding.def.PassThroughComponent.genContentUnmarshal(PassThroughComponent.java:111)
[bind] at org.jibx.binding.def.MappingReference.genContentUnmarshal(MappingReference.java:223)
[bind] at org.jibx.binding.def.NestedCollection.genContentUnmarshal(NestedCollection.java:167)
[bind] at org.jibx.binding.def.ObjectBinding.genUnmarshalContentCall(ObjectBinding.java:798)
[bind] at org.jibx.binding.def.ObjectBinding.genContentUnmarshal(ObjectBinding.java:943)
[bind] at org.jibx.binding.def.ComponentProperty.genContentUnmarshal(ComponentProperty.java:271)
[bind] at org.jibx.binding.def.NestedStructure.genContentUnmarshal(NestedStructure.java:190)
[bind] at org.jibx.binding.def.ObjectBinding.genUnmarshalContentCall(ObjectBinding.java:798)
[bind] at org.jibx.binding.def.ObjectBinding.genContentUnmarshal(ObjectBinding.java:943)
[bind] at org.jibx.binding.def.PassThroughComponent.genContentUnmarshal(PassThroughComponent.java:111)
[bind] at org.jibx.binding.def.BaseMappingWrapper.genContentUnmarshal(BaseMappingWrapper.java:73)
[bind] at org.jibx.binding.def.PassThroughComponent.genContentUnmarshal(PassThroughComponent.java:111)
[bind] at org.jibx.binding.def.MappingReference.genContentUnmarshal(MappingReference.java:223)
[bind] at org.jibx.binding.def.NestedStructure.genContentUnmarshal(NestedStructure.java:190)
[bind] at org.jibx.binding.def.ObjectBinding.genUnmarshalContentCall(ObjectBinding.java:798)
[bind] at org.jibx.binding.def.ObjectBinding.genContentUnmarshal(ObjectBinding.java:943)
[bind] at org.jibx.binding.def.ElementWrapper.genContentUnmarshal(ElementWrapper.java:314)
[bind] at org.jibx.binding.def.MappingDefinition.generateUnmarshalImplementation(MappingDefinition.java:640)
[bind] at org.jibx.binding.def.MappingDefinition.generateCode(MappingDefinition.java:851)
[bind] at org.jibx.binding.def.DefinitionContext.generateCode(DefinitionContext.java:669)
[bind] at org.jibx.binding.def.BindingDefinition.generateCode(BindingDefinition.java:661)
[bind] at org.jibx.binding.Compile.compile(Compile.java:305)
[bind] at org.jibx.binding.ant.CompileTask.execute(CompileTask.java:248)
[bind] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
[bind] at org.apache.tools.ant.Task.perform(Task.java:364)
[bind] at org.apache.tools.ant.Target.execute(Target.java:341)
[bind] at org.apache.tools.ant.Target.performTasks(Target.java:369)
[bind] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
[bind] at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
[bind] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
[bind] at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32)
[bind] at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
[bind] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423)
[bind] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137)