The renderer has historically supported the construction where the fields for a UIMessage may themselves be a UIBound - for example in the form
which allows the resolution of an I18N message to be geared through a model. However, there is a "fault" in the implementation of the protocomponent expander, that it is not possible to take advantage of this facility by means of writing a UIMessage protocomponent with EL reference that expands to this form - for example the following construction
fails to expand properly (although "args") are expanded. This patch corrects the protocomponent expander so that the messagekey member of UIMessage is expanded as if it were a UIBound.