private void firePropertyChangeEvent(PropertyChangeEvent ev) {
		// notify listeners of tool change
		for (WorkspaceChangeListener l : changeListeners) {
			l.propertyChange(ev);
		}
	}
Get the key for the connection map.

@param producer tool producing an event
@param consumer tool consuming an event
Ghidra/Framework/Project/src/main/java/ghidra/framework/project/tool/ToolManagerImpl.java