private SubMemoryBlock getSubBlock(long offset) {
		// avoid potential thread race condition
		SubMemoryBlock last = lastSubBlock;
		if (last != null && last.contains(offset)) {
			return last;
		}
		last = findBlock(0, subBlocks.size() - 1, offset);
		lastSubBlock = last;
		return last;
	}
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