ImmutableDescriptor.getFieldValues(non-empty-array) on an empty descriptor returns unexpected array

modelmbean.DescriptorSupport behaves as expected but ImmutableDescriptor not despite the method under test is defined in the Descriptor interface they both implement.
The failing test case is based on the javadoc sentence "If the descriptor is empty, you will get an empty array.".
The test does:

Descriptor descr = new ImmutableDescriptor(new String[]{}, new Object[]{});
descr.getFieldValues(new String[]{"missing", "in", "action"}).

I put here the JCK test output :

(TEST) Retrieval with a non empty array on an empty Descriptor
(ERROR) Field values not as expected
 GOT = [null, null, null]
 EXPECTED = []


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