void addParent(FidHashQuad parent) {
		Long key = parent.getFullHash();		// Parents should be unique only up to the full hash
		this.parents.put(key, parent);
	}
Container class for the neighborhood of hashes around a function.  Contains
the FidHashQuad for the function, for all its parents (callers), all its children (callees),
and all the names of the children whose hashes could not be resolved.
Ghidra/Features/FunctionID/src/main/java/ghidra/feature/fid/service/HashFamily.java