protected Iterator<T> iterator(int columnIndex, FieldSpan fieldSpan, Direction direction)
			throws IOException {
		DirectedRecordIterator it =
			DirectedRecordIterator.getIndexIterator(table, columnIndex, fieldSpan, direction);
		return objects.iterator(it);
	}
Search a column index and iterate over objects having the given value

@param columnIndex the indexed column's number
@param fieldSpan required: the range to consider
@param direction the direction of iteration
@return the iterator, possibly empty but never null
@throws IOException if there's an issue reading the table
Ghidra/Debug/ProposedUtils/src/main/java/ghidra/util/database/DBCachedObjectStore.java