### Question:
DocumentClientException extends Exception { public Map<String, String> getResponseHeaders() { return this.responseHeaders; } DocumentClientException(int statusCode);  DocumentClientException(int statusCode, String errorMessage);  DocumentClientException(int statusCode, Exception innerException);  DocumentClientException(int statusCode, Error errorResource, Map<String, String> responseHeaders);  DocumentClientException(
        String resourceAddress, int statusCode, Error errorResource, Map<String, String> responseHeaders);  DocumentClientException(
        String message,
        Exception exception,
        Map<String, String> responseHeaders,
        int statusCode,
        String resourceAddress); private  DocumentClientException(
        int statusCode, String message, Map<String, String> responseHeaders, Throwable cause); String getActivityId(); ClientSideRequestStatistics getClientSideRequestStatistics(); void setClientSideRequestStatistics(ClientSideRequestStatistics clientSideRequestStatistics); Error getError(); long getLsn(); @Override String getMessage(); String getPartitionKeyRangeId(); Map<String, String> getRequestHeaders(); Uri getRequestUri(); void setRequestUri(Uri requestUri); Map<String, String> getResponseHeaders(); long getRetryAfterInMilliseconds(); int getStatusCode(); int getSubStatusCode(); @Override String toString();  }### Answer:
@Test(groups = { "unit" }) public void headerNotNull1() { DocumentClientException dce = new DocumentClientException(0); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).isEmpty(); }
@Test(groups = { "unit" }) public void headerNotNull2() { DocumentClientException dce = new DocumentClientException(0, "dummy"); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).isEmpty(); }
@Test(groups = { "unit" }) public void headerNotNull3() { DocumentClientException dce = new DocumentClientException(0, new RuntimeException()); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).isEmpty(); }
@Test(groups = { "unit" }) public void headerNotNull4() { DocumentClientException dce = new DocumentClientException(0, (Error) null, (Map) null); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).isEmpty(); }
@Test(groups = { "unit" }) public void headerNotNull5() { DocumentClientException dce = new DocumentClientException((String) null, 0, (Error) null, (Map) null); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).isEmpty(); }
@Test(groups = { "unit" }) public void headerNotNull6() { DocumentClientException dce = new DocumentClientException((String) null, (Exception) null, (Map) null, 0, (String) null); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).isEmpty(); }
@Test(groups = { "unit" }) public void headerNotNull7() { ImmutableMap<String, String> respHeaders = ImmutableMap.of("key", "value"); DocumentClientException dce = new DocumentClientException((String) null, (Exception) null, respHeaders, 0, (String) null); assertThat(dce.getResponseHeaders()).isNotNull(); assertThat(dce.getResponseHeaders()).contains(respHeaders.entrySet().iterator().next()); }