According to the spec:
XML schema does not define an empty sequence that is the content of a complex type as effective content so any DFDL annotations on such a construct would be ignored. It is a schema definition error if the empty sequence is the content of a complex type.

I set this up in test emptySequenceSDE, but there is no error:

[info] - test_emptySequenceSDE *** FAILED ***
[info] java.lang.Exception: Expected error. Didn't get one. Actual result was <emptySeq></emptySeq>
[info] at edu.illinois.ncsa.daffodil.tdml.ParserTestCase.runParseExpectErrors(TDMLRunner.scala:479)
[info] at edu.illinois.ncsa.daffodil.tdml.ParserTestCase.runProcessor(TDMLRunner.scala:402)
[info] at edu.illinois.ncsa.daffodil.tdml.TestCase.run(TDMLRunner.scala:350)
[info] at edu.illinois.ncsa.daffodil.tdml.DFDLTestSuite.runOneTestWithDataVolumes(TDMLRunner.scala:222)
[info] at edu.illinois.ncsa.daffodil.tdml.DFDLTestSuite.runOneTest(TDMLRunner.scala:213)
[info] at edu.illinois.ncsa.daffodil.section14.sequence_groups.TestSequenceGroups.test_emptySequenceSDE(TestSequenceGroups.scala:77)
[info] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[info] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
[info] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[info] at java.lang.reflect.Method.invoke(Method.java:601)

The test is emptySequenceSDE in the following files:
daffodil-test/src/test/resources/edu/illinois/ncsa/daffodil/section14/sequence_groups/SequenceGroup.tdml
daffodil-test/src/test/scala-debug/edu/illinois/ncsa/daffodil/section14/sequence_groups/TestSequenceGroupsDebug.scala
daffodil-test/src/test/scala/edu/illinois/ncsa/daffodil/section14/sequence_groups/TestSequenceGroups.scala