AnnotationFS pointer = cas.createAnnotation(frameType, begin, begin);
FSIterator iterator = cas.getAnnotationIndex().iterator(pointer);
int nextEnd = -1;
// ???
iterator.moveToPrevious();
iterator.moveToPrevious();
while (iterator.isValid()) {
FeatureStructure fs = iterator.get();
if (fs instanceof AnnotationFS) {
AnnotationFS a = (AnnotationFS) fs;