There's a flaw in org.apache.geronimo.system.configuration.GBeanOverride:
getValue(), lines 388-389:
PropertyEditor editor = loadPropertyEditor(attribute, classLoader);
loadPropertyEditor() may return null (lines 402, 407) and this can cause NPE.
I didn't see this NPE on Sun, but it occurs on Harmony (clearly some other issue exists causing the loadPropertyEditor() to return null, investigating) and I think it's a problem anyway.