### Question:
ConstantModule implements AtlasModule { @Override public String getDocId() { return null; }  @Override void init(); @Override void destroy(); @Override void setClassLoader(ClassLoader classLoader); @Override ClassLoader getClassLoader(); @Override void processPreValidation(AtlasInternalSession session); @Override void processPreSourceExecution(AtlasInternalSession session); @Override void readSourceValue(AtlasInternalSession session); @Override void processPostSourceExecution(AtlasInternalSession session); @Override void processPreTargetExecution(AtlasInternalSession session); @Override void populateTargetField(AtlasInternalSession session); @Override void writeTargetValue(AtlasInternalSession session); @Override void processPostTargetExecution(AtlasInternalSession session); @Override void processPostValidation(AtlasInternalSession session); @Override AtlasModuleMode getMode(); @Override void setMode(AtlasModuleMode atlasModuleMode); @Override AtlasConversionService getConversionService(); @Override void setConversionService(AtlasConversionService atlasConversionService); @Override List<AtlasModuleMode> listSupportedModes(); @Override String getDocId(); @Override void setDocId(String docId); @Override String getUri(); @Override void setUri(String uri); @Override Boolean isStatisticsSupported(); @Override Boolean isStatisticsEnabled(); @Override Boolean isSupportedField(Field field); @Override Field cloneField(Field field); @Override AtlasFieldActionService getFieldActionService(); @Override void setFieldActionService(AtlasFieldActionService atlasFieldActionService); AtlasCollectionHelper getCollectionHelper(); @Override String getUriDataType(); @Override Map<String, String> getUriParameters(); @Override void setDataSourceMetadata(DataSourceMetadata meta); @Override DataSourceMetadata getDataSourceMetadata();  }### Answer:
@Test public void testGetDocId() { assertNull(module.getDocId()); }