@Override
	protected void programClosed(Program program) {
		for (InstructionInfoProvider provider : new ArrayList<>(disconnectedProviders)) {
			if (provider.getProgram() == program) {
				remove(provider);
			}
		}
	}
Subclass should override this method if it is interested in
program location events.
@param loc location could be null
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/processors/ShowInstructionInfoPlugin.java