ModelElementTypeBuilder typeBuilder = modelBuilder.defineType(ItemAwareElement.class, BPMN_ELEMENT_ITEM_AWARE_ELEMENT)
.namespaceUri(BPMN20_NS)
.extendsType(BaseElement.class)
.abstractType();
itemSubjectRefAttribute = typeBuilder.stringAttribute(BPMN_ATTRIBUTE_ITEM_SUBJECT_REF)
.qNameAttributeReference(ItemDefinition.class)
.build();
SequenceBuilder sequenceBuilder = typeBuilder.sequence();