private void removeExternalLibrary(Program program, String libName)
			throws InvalidInputException {
		ExternalManager extMgr = program.getExternalManager();
		ExternalLocationIterator iter = extMgr.getExternalLocations(libName);
		if (iter.hasNext()) {
			throw new InvalidInputException(
				"Didn't remove external library " + libName + " since it isn't empty.");
		}
		if (!extMgr.removeExternalLibrary(libName)) {
			throw new InvalidInputException("Didn't remove external library " + libName);
		}
	}
Removes the indicated external library from the indicated program version
if it is empty.
@param program the program
@param libName the external library name
@throws InvalidInputException if there is no such enterrnal library in the program
Ghidra/Features/Base/src/main/java/ghidra/app/merge/listing/ExternalProgramMerger.java