### Question:
CallbackHeader { @Override public String toString() { return "CallbackHeader [requestId=" + requestId + ", responseCode=" + responseCode + ", responseMessage=" + responseMessage + "]"; } CallbackHeader();  CallbackHeader(String reqId, String respCode, String respMsg); String getRequestId(); void setRequestId(String value); String getResponseCode(); void setResponseCode(String value); String getResponseMessage(); void setResponseMessage(String value); @Override String toString();  }### Answer:
@Test public void testtoString() { assertNotNull(cb.toString()); }