private void possiblyMergeSubBlocks(int lastOld, int firstNew) throws IOException {
		SubMemoryBlock sub1 = subBlocks.get(lastOld);
		SubMemoryBlock sub2 = subBlocks.get(firstNew);
		if (sub1.join(sub2)) {
			subBlocks.remove(firstNew);
		}
	}
Get collection of blocks which map onto this block.

@return collection of blocks which map onto this block or null if none identified
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/mem/MemoryBlockDB.java