void removeProvider(CallTreeProvider provider) {
		if (!providers.contains(provider)) {
			// already been removed (this sometimes happens twice, as this happens when providers
			// are closed by the user and when they are removed from the tool due to disposal)
			return;
		}

		providers.remove(provider);
		tool.removeComponentProvider(provider);
		provider.dispose();
	}
Assuming a function <b>foo</b>, this plugin will show:
 1) all callers of <b>foo</b> 
 2) all functions which reference <b>foo</b>
 3) all callees of <b>foo</b>
 4) all functions referenced by <b>foo</b>.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/calltree/CallTreePlugin.java