### Question:
BpmnModelExporter { public String toBpmnXml(FlowBuilder flowBuilder) { return toBpmnXml(flowBuilder.getDefinition()); }  BpmnModel toBpmnModel(FlowBuilder flowBuilder); BpmnModel toBpmnModel(FlowDefinition definition); String toBpmnXml(FlowBuilder flowBuilder); String toBpmnXml(FlowDefinition definition); String toBpmnXml(BpmnModel bpmnModel);  }### Answer:
@Test public void shouldTransformToBpmnXmlString() throws IOException { BpmnModelExporter bpmnModelExporter = new BpmnModelExporter(); FlowBuilder emptyFlow = new BpmnFlowBuilder() { @Override public void define() {} @Override public String getId() { return "emptyFlow"; } }; String bpmnXml = bpmnModelExporter.toBpmnXml(emptyFlow); assertThat(bpmnXml).isEqualTo(emptyFlowContent()); }