Internal JiBX error

I'm trying to build a map of objects, so I"m keeping a linked list (for the order) + a map.
This makes JiBX very unhappy.

The relevant part of my binding.xml is:

<collection field="files" add-method="addFile" item-type="com.td.ais.dataimport.FileMeta" />

The Java bit:

public class ImportMeta extends BaseValueObject {
public static class FileList extends ArrayList {
private final Map map = new HashMap();
void addFile(FileMeta fileMeta)

}
private final FileList files = new FileList();
....
}

Here is the problem:

[java] Error running binding compiler
[java]
[java] *** Error during code generation - please report this error on the JiBX users list so that the condition can be caught during validation ***
[java]
[java] java.lang.IllegalStateException: Internal error: Expected com.td.ais.dataimport.FileMeta on stack, found java.lang.Object
[java] full stack:
[java] 0: com.td.ais.dataimport.ImportMeta$FileList
[java] 1: com.td.ais.dataimport.ImportMeta$FileList
[java] 2: java.lang.Object
[java]
[java] at org.jibx.binding.classes.MethodBuilder.verifyCompatible(MethodBuilder.java:409)
[java] at org.jibx.binding.classes.MethodBuilder.verifyCallStack(MethodBuilder.java:480)
[java] at org.jibx.binding.classes.MethodBuilder.verifyCallStack(MethodBuilder.java:501)
[java] at org.jibx.binding.classes.MethodBuilder.appendCall(MethodBuilder.java:808)
[java] at org.jibx.binding.def.NestedCollection$AddStore.genStoreItem(NestedCollection.java:666)
[java] at org.jibx.binding.def.NestedCollection.genContentUnmarshal(NestedCollection.java:133)
[java] at org.jibx.binding.def.ObjectBinding.genUnmarshalContentCall(ObjectBinding.java:736)
[java] at org.jibx.binding.def.ObjectBinding.genContentUnmarshal(ObjectBinding.java:875)
[java] at org.jibx.binding.def.ComponentProperty.genContentUnmarshal(ComponentProperty.java:237)
[java] at org.jibx.binding.def.NestedStructure.genContentUnmarshal(NestedStructure.java:153)
[java] at org.jibx.binding.def.ObjectBinding.genUnmarshalContentCall(ObjectBinding.java:736)
[java] at org.jibx.binding.def.ObjectBinding.genContentUnmarshal(ObjectBinding.java:875)
[java] at org.jibx.binding.def.ElementWrapper.genContentUnmarshal(ElementWrapper.java:272)
[java] at org.jibx.binding.def.MappingDefinition.generateCode(MappingDefinition.java:541)
[java] at org.jibx.binding.def.DefinitionContext.generateCode(DefinitionContext.java:600)
[java] at org.jibx.binding.def.BindingDefinition.generateCode(BindingDefinition.java:578)
[java] at org.jibx.binding.Compile.compile(Compile.java:303)
[java] at org.jibx.binding.Compile.main(Compile.java:382)