Compatibility with SF 3.2.2
Previously the filter returned a Collections.singletonList() when
a match is found.
Spring 3.2.2 attempts to sort the results of MethodFilter.filter()
which fails because the list is immutable.
Continue to return Collections.emptyList() with no match; this
does not cause the sort to fail.
Several tests in MethodInvokingMessageProcessorTests reproduce this
problem with Spring 3.2.2.
Add a test to confirm the Collections.emptyList() does not cause
any problems.
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