new String[]{"a"},
new String[]{},
new String[]{"a","b"}},config,converter));
PTASequenceSet d = new PTASequenceSet();
d.addAll(buildSet(new String[][] {
new String[]{"a","c","d"},
new String[]{"a"},
new String[]{"a"}},config,converter));
c.addAll(d);
Set<List<Label>> expected = buildSet(new String[][]{