protected void validate() throws ContainerInitializationException {
        List<String> errFields = new ArrayList<>();
        if (requestTypeClass == null) {
            errFields.add("request type class");
        }
        if (responseTypeClass == null) {
            errFields.add("response type class");
        }
        if (requestReader == null) {
            errFields.add("request reader");
        }
        if (responseWriter == null) {
            errFields.add("response writer");
        }
        if (securityContextWriter == null) {
            errFields.add("security context writer");
        }
        if (exceptionHandler == null) {
            errFields.add("exception handler");
        }
        if (initializationWrapper == null) {
            errFields.add("initialization wrapper");
        }
        if (!errFields.isEmpty()) {
            throw new ContainerInitializationException(String.format(MISSING_FIELD_ERROR, String.join(", ", errFields)), null);
        }
    }
@Test
    void validation_throwsException() {
        TestBuilder testBuilder = new TestBuilder();
        try {
            testBuilder.validate();
        } catch (ContainerInitializationException e) {
            return;
        }
        fail("Did not throw exception");
    }