mvvmfx/src/main/java/de/saxsys/mvvmfx/internal/viewloader/ResourceBundleManager.java
public ResourceBundle mergeWithGlobal(ResourceBundle resourceBundle) {
		if (globalResourceBundle == null) {
			if (resourceBundle == null) {
				return EMPTY_RESOURCE_BUNDLE;
			} else {
				return new ResourceBundleWrapper(resourceBundle);
			}
		} else {
			if (resourceBundle == null) {
				return new ResourceBundleWrapper(globalResourceBundle);
			} else {
				return merge(resourceBundle, globalResourceBundle);
			}
		}
	}
public ResourceBundle mergeWithGlobal(ResourceBundle resourceBundle) {
		if (globalResourceBundle == null) {
			if (resourceBundle == null) {
				return EMPTY_RESOURCE_BUNDLE;
			} else {
				return new ResourceBundleWrapper(resourceBundle);
			}
		} else {
			if (resourceBundle == null) {
				return new ResourceBundleWrapper(globalResourceBundle);
			} else {
				return merge(resourceBundle, globalResourceBundle);
			}
		}
	}
Merges the provided ResourceBundle with the global one (if any).

The global resourceBundle has a lower priority then the provided one. If there is the same key defined in the
global and the provided resourceBundle, the value from the provided resourceBundle will be used.

@param resourceBundle
a resourceBundle that will be merged.
@return the merged resourceBundle or null, if there is no global resource bundle and not given resource bundle.