private CompletableFuture<Boolean> getModuleCloseable(WorkbenchModule module) {
        return moduleCloseableMap.get(module);
    }
Returns a {@link CompletableFuture}, which upon completion will cause the module to be closed
and if there was an ongoing stage closing process, it will re-initiate that process.
workbenchfx-core/src/main/java/com/dlsc/workbenchfx/Workbench.java