HeaderMetaData { public boolean isEmpty() { return patternsByColumnNumber.isEmpty(); } HeaderMetaData(@MapsTo("patternsByColumnNumber") final Map<Integer, ModelMetaData> patternsByColumnNumber); ModelMetaData getPatternsByColumnNumber(final Integer columnIndex); int size(); boolean isEmpty(); Set<Integer> keySet();  }
@Test public void isEmpty() throws Exception { assertTrue(new HeaderMetaData(new HashMap<>()).isEmpty()); }