### Question:
ProcessModelContentConverter implements ModelContentConverter<BpmnProcessModelContent> { @Override public FileContent overrideModelId(FileContent fileContent, Map<String, String> modelIdentifiers) { FileContent newFileContent; Optional<BpmnProcessModelContent> processModelContent = this.convertToModelContent(fileContent.getFileContent()); if (processModelContent.isPresent()) { BpmnProcessModelContent modelContent = processModelContent.get(); ReferenceIdOverrider referenceIdOverrider = new ReferenceIdOverrider(modelIdentifiers); this.overrideAllProcessDefinition(modelContent, referenceIdOverrider); byte[] overriddenContent = this.convertToBytes(modelContent); newFileContent = new FileContent(fileContent.getFilename(), fileContent.getContentType(), overriddenContent); } else { newFileContent = fileContent; } return newFileContent; } ProcessModelContentConverter(ProcessModelType processModelType,
                                        BpmnXMLConverter bpmnConverter); @Override ModelType getHandledModelType(); @Override Optional<BpmnProcessModelContent> convertToModelContent(byte[] bytes); @Override byte[] convertToBytes(BpmnProcessModelContent bpmnProcessModelContent); Optional<BpmnProcessModelContent> convertToModelContent(BpmnModel bpmnModel); BpmnModel convertToBpmnModel(byte[] modelContent); @Override FileContent overrideModelId(FileContent fileContent,
                                       Map<String, String> modelIdentifiers); void overrideAllProcessDefinition(BpmnProcessModelContent processModelContent,
                                             ReferenceIdOverrider referenceIdOverrider);  }### Answer:
@Test public void should_notOverrideModelId_whenModelContentEmpty() { FileContent fileContent = mock(FileContent.class); byte[] emptyByteArray = new byte[0]; given(fileContent.getFileContent()).willReturn(emptyByteArray); Map<String, String> modelIds = new HashMap<>(); FileContent result = processModelContentConverter.overrideModelId(fileContent, modelIds); assertThat(result).isSameAs(fileContent); }