### Question:
OkCancelDialog extends Window { @SuppressFBWarnings(value = "RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE", justification = "yeah, we know...") @Override public void setContent(@CheckForNull Component content) { if (mainArea == null) { super.setContent(content); } else { mainArea.removeAllComponents(); mainArea.addComponent(content); } } protected  OkCancelDialog(String caption, Handler okHandler, Handler cancelHandler,
            ButtonOption buttonOption, Component... contentComponents); @Deprecated  OkCancelDialog(String caption); @Deprecated  OkCancelDialog(String caption, Handler okHandler); @Deprecated  OkCancelDialog(String caption, Handler okHandler, ButtonOption buttonOption); @Deprecated  OkCancelDialog(String caption, Component content, Handler okHandler, ButtonOption buttonOption); @SuppressFBWarnings(value = "RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE", justification = "yeah, we know...") @Override void setContent(@CheckForNull Component content); void setSize(String width, String height); MessageList validate(); ValidationService getValidationService(); void setValidationService(ValidationService validationService); void setBeforeOkHandler(Handler beforeOkHandler); OkCancelDialog open(); void addContent(Component c); void addContent(Component c, float expandRatio); boolean isOkPressed(); ValidationDisplayState getValidationDisplayState(); boolean isCancelPressed(); static Builder builder(String caption);  }### Answer:
@Test public void testSetContent() { OkCancelDialog dialog = OkCancelDialog.builder("").build(); assertThat(DialogTestUtil.getContents(dialog).size(), is(0)); dialog.setContent(new Label()); assertThat(DialogTestUtil.getContents(dialog), hasSize(1)); assertThat(dialog, is(showingEnabledOkButton())); }