public String getLoadWarning(final String canonicalPluginName) {
        return lastLoadWarnings.get(canonicalPluginName);
    }
Returns a human-readable, localized message related to a failure while trying to load a plugin. When the last
time that this plugin was loaded was successful (or when a plugin of this name was never attempted to be loaded
at all), this method returns null.

@param canonicalPluginName The canonical name of a plugin
@return An optional human-readable, localized failure message.
xmppserver/src/main/java/org/jivesoftware/openfire/container/PluginManager.java