private String fixupOverlaySpaceName(String blockName) {
		int len = blockName.length();
		StringBuffer buf = new StringBuffer(len);
		for (int i = 0; i < len; i++) {
			char c = blockName.charAt(i);
			if (c == ':' || c <= 0x20) {
				buf.append('_');
			}
			else {
				buf.append(c);
			}
		}
		return buf.toString();
	}
Generate an allowed address space name from a block name. Use of unsupported characters will
be converted to underscore (includes colon and all whitespace chars). double-underscore to
ensure uniqueness.

@param blockName corresponding memory block name
@return overlay space name
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/mem/MemoryMapDB.java