since 7 PropertyEditor doesn't return "null" but null on null value. this causes misunderstanding, for example, two JCK tests became invalid.

api/java_beans/PropertyEditorSupport/descriptions.html#EditorSupport[PropertyEditorSupport0008]
api/java_beans/PropertyEditorSupport/descriptions.html#EditorSupport[PropertyEditorSupport0009]

spec should contain explanation what "the value can't be expressed as a string" is, probably, example.